How to solve trigonometry identities! (ultimate practice)

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  • Опубліковано 28 вер 2024

КОМЕНТАРІ • 159

  • @sohampinemath1086
    @sohampinemath1086 Рік тому +93

    Timestamps below 😊😊
    1) 0:32
    2) 4:42
    3) 7:15
    4) 9:04
    5) 10:47
    6) 13:01
    7) 15:36
    8) 19:10
    9) 24:12
    10) 29:33
    11) 32:40
    12) 36:55
    13) 42:46
    14) 45:41
    15) 49:41
    16) 57:25
    17) 1:02:07
    18 ) 1:04:49
    19) 1:07:29
    20) 1:12:09
    21) 1:16:11
    22) 1:14:50
    23) 1:20:21
    24) 1:23:58
    100 differential equations please❤❤

  • @ayssinaattori9313
    @ayssinaattori9313 Рік тому +12

    We just started doing trig equations in school and I realised how fun it is to play around with trig identities. Really glad I found this video, it was really fun and I became more familiar with with other trig functions than sin, cos, and tan, which are the ones we've manly had thus far.

  • @NoahMartin-ii1wz
    @NoahMartin-ii1wz Рік тому +121

    do 200 trig equations/inequalities in one take as fast as you can 😂😂

    • @L17_8
      @L17_8 Рік тому +11

      Jesus loves you ❤️ please turn to him and repent before it's too late. The end times described in the Bible are already happening in the world.

    • @NoahMartin-ii1wz
      @NoahMartin-ii1wz Рік тому

      make it logarithmic equations/inequalities LOLL@@L17_8

    • @user-fh2rw9zh8g
      @user-fh2rw9zh8g Рік тому +2

      I wish he doooesss I'm currently self studying trigonometry and this would be so helpful

    • @robertcampomizzi7988
      @robertcampomizzi7988 11 місяців тому +2

      Listen to the very last line of "Alphabet Aerobics" by Blackalicious and you'll know why I think you should.

    • @robertcampomizzi7988
      @robertcampomizzi7988 11 місяців тому +5

      ​​@@L17_8if Jesus was a carpenter then he used trigonometry. Why didn't they write that trig down in the Bible? I'm just asking questions.

  • @ayssinaattori9313
    @ayssinaattori9313 Рік тому +7

    Finished the video now, took some breaks in between. Was able to get most questions on my own but it was really fun to see how our ways of solving them differed. Especially on questions 16 and 17 I overcomplicated it a lot but I did end up at the right answer. Tank you so much!

  • @hawtpotato90210
    @hawtpotato90210 7 місяців тому +3

    42:40 I am with you brother. I am doing my best on the problems and you're filling in the gaps as I work on this over the course of a few days. Your videos have been valuable to my efforts to strengthen my math skills. Thank you very very very much BpRp!

    • @blackpenredpen
      @blackpenredpen  7 місяців тому +1

      Glad to hear!! Keep up your good work and best wishes to you!

  • @professionalgster1176
    @professionalgster1176 4 місяці тому

    Thank you so much for explaining well, I was assigned this today and was so confused and SCARED haha. Watched over 2 of your problems and I'm starting to understand!

  • @saurabpoudel9134
    @saurabpoudel9134 Рік тому +2

    Thanks professor ! Please also make video on analytical geometry

  • @r.i.p.volodya
    @r.i.p.volodya Рік тому

    Many THANKS for all the time you put into your videos. I find you inspirational 😁

  • @jaii5955
    @jaii5955 Рік тому +2

    I definitely loved your math questions ❤😮

  • @ahmet00fx
    @ahmet00fx 7 місяців тому

    i am a 12th grade student in Turkey and these questions are way easy than I expected.

  • @Subham-Kun
    @Subham-Kun 10 місяців тому +1

    49:24 "If I did my math right" - If this man makes mistakes in addition, I am allergic to numbers

  • @ManasvinShrimali
    @ManasvinShrimali Рік тому

    at 14:37 sir you can also write 2sin^2(x) as sin^2(x) + sin^2(x) + cos^2(x) - 1=sin^2(x)

  • @carterbagvitch5964
    @carterbagvitch5964 Рік тому +1

    I ran into an interesting trig problem on my no calculator pre-calc/alg 2 test and was wondering how to do it since I only had solutions and all my teachers said there had to be a trick they didn’t know. The problem was
    If sin(x)+cos(x)=1/3, what does ((sin(x))^5)+((cos(x))^5)=

    • @adamhurt6140
      @adamhurt6140 Рік тому

      what was the answer they gave you?

    • @carterbagvitch5964
      @carterbagvitch5964 Рік тому +1

      @@adamhurt6140 I figured it out. The answer was 344, but thats cause they asked for the answer in fractional form (k/w), and then the answer is k+w. thats obviously not a critical step, so I didnt include it. If you want to know, u take pascals triangle and expand it out with sin(x) and cos(x), isolate sin^5(x) +cos^5(x), then factor and break down the rest of it using trig identities and the given. Also have to realize that since sin(x)+cos(x)=1/3, cos(x)*sin(x)=-4/9. thats also key

  • @antonioaccogli1014
    @antonioaccogli1014 11 місяців тому

    I am doing to do your test to repeat for my school test... i will tell you how it will go

  • @notboboi9977
    @notboboi9977 6 місяців тому +1

    1:06
    if u look at the captions..
    cosx over se-

  • @suryatejacv3042
    @suryatejacv3042 6 місяців тому

    Hai sir can you discuss telescopic sums with alternating positive negative sums

  • @vivekgupT______________
    @vivekgupT______________ Рік тому +2

    Bro you are awesome I love you ❤❤ I am from india and I am like maths

  • @marshallmanz123
    @marshallmanz123 Рік тому

    You deserve more views man.

  • @FVerz
    @FVerz 11 місяців тому

    26:34 Bro acts like he just made the height of 2 tall buildings approach 0m in 2001

  • @talentlogic1512
    @talentlogic1512 11 місяців тому +1

    I like this a lot. Thank you my friend.

  • @humester
    @humester 29 днів тому

    Q17: [tan(x)+tan(y)]/[1-tan(x)tan(y)]=tan(x+y). So, tan(x)+tan(y)=tan(x+y)[1-tan(x)tan(y)] Is it necessary to reduce to sines and cosines?
    {sin(x+y)[1-(sinx/cosy)*(siny/cosy)]}/cos(x+y)=sin(x+y)[cos(x)cos(y)-sin(x)sin(y)]/[cos(x+y)cos(x)cos(y)]=sin(x+y)cos(x+y)/[cos(x+y)cos(x)cos(y)]=sin(x+y)/cos(x)cos(y)

  • @nemanjalazarevic9249
    @nemanjalazarevic9249 11 місяців тому

    My take:
    1. sinx +cotxcosx = sinx +(cos^2x/sinx) = (sin^2x + cos^2x/sinx) = 1/sinx = cscx
    2. (1-cos^2x)/sinxcosx = tanx
    3.cosx/sinx(1/sinx - sinx) = cosx/1-sin^2x = secx
    4:1+2cosx/2+secx = 1+2cosx/2+1/cosx = cosx+2cos^2x/2cosx+1 =cosx(2cosx+1)/2cosx+1 = cosx
    5:1+sinx/(1-sinx)(1+sinx) + 1-sinx/(1-sinx)(1+sinx) = 2/cos^2x = 2sec^2x

  • @lordpz3518
    @lordpz3518 4 місяці тому

    plz teach mathematicalinduction

  • @Tomuchfanforfon
    @Tomuchfanforfon Рік тому

    Good teacher watching from india guys reply where are you watching from?

    • @carultch
      @carultch 8 місяців тому

      I like your Nepal flag.

  • @dinoortolani6794
    @dinoortolani6794 Рік тому

    you're amazing thanks

  • @CoconutChor
    @CoconutChor Рік тому

    Ok time to do some maths

  • @Subham-Kun
    @Subham-Kun 10 місяців тому

    26:20 It is unbelievable that even the GOAT of Mathematics, who alone is strong enough to beat Lord Wolfram|Alpha, is lagging!!!!!!!!!!! THIS IS ALARMING FOR THE DIMENSION OF MATHEMATICS!!!!!!!!!!!!

  • @Voxel79
    @Voxel79 Рік тому

    Just for geeks like me watching this video... Here's a stupid math idea I created to calculate solutions for cos(x) returning bigger numbers than 1 just calculating them in your head:
    There's multiple solutions that can be calculated in your head, but this is a puzzle for you guys... (I'm an a*hole ;P)
    Lets take 17... its odd number. divide by 2 and round it down&up to get 8&9 => a=17; b=8; c=9:
    cos(17)=cos(ln(17+12sqrt(2))i)
    a: 17
    b: factors made by 2*2*2 so we can get 2 out of sqrt leaving just 2 inside
    c: factors made by 3*3 so we can get 3 out of sqrt leving just 1 insede
    d: left out of sqrt multiplied 2*3=6
    e: left inside sqrt multiplied 1*2=2
    cos(a)=cos(ln(a+2d*sqrt(e))i)
    Lets take 100... its even number. add and subtract 1 to get 99&101 => a=100 b=99 c=101
    cos(100)=cos(ln(100+3sqrt(1111))i)
    a: 100
    b: factors made by 3*3*11 so we can get 3 out of sqrt leaving just 3 inside
    c: factors 101
    e: left out of sqrt mutiplied 3
    d: left inside sqrt multiplied 11*101=1111
    cos(a)=cos(ln(a+b*sqrt(d))i)

  • @blackpenredpen
    @blackpenredpen  Рік тому +73

    Could someone please help me do the time stamps because it will really help all the viewers to navigate the video? I will also credit your name in the description. Thank you.

    • @shishirjha4219
      @shishirjha4219 Рік тому +6

      Ok then you have to wait for an hour and a half and I don't need any credits

    • @thatomofolo452
      @thatomofolo452 Рік тому +1

      Chain effect 👍👍😁

    • @L17_8
      @L17_8 Рік тому +3

      Jesus loves you ❤️ please turn to him and repent before it's too late. The end times described in the Bible are already happening in the world.

    • @shishirjha4219
      @shishirjha4219 Рік тому

      @@L17_8 bro is on drugs

    • @thenew3dworldfan
      @thenew3dworldfan Рік тому

      I have a question. Suppose a(n) is the integer sequence A007916. Does the series (1 to inf) 1/ (A007916(n))^2 conv or div?

  • @ahsonkusare2352
    @ahsonkusare2352 Рік тому +27

    Please next videos:24 indefinite integrals and
    24 definite integrals
    (High level problems)
    And happy teachers day

  • @imaginaryangle
    @imaginaryangle Рік тому +64

    The amount of care you take that the viewer really gets it and doesn't trip over a step you are making is absolutely amazing

  • @danielputrahandana2982
    @danielputrahandana2982 Рік тому +4

    I watch these while eating because I dont know what Video to watch

  • @kylewaddle7592
    @kylewaddle7592 Рік тому +8

    I dont comment often but i felt that i should mention how helpful and entertaining with me learning calculus and other math. Also i loved this video

    • @blackpenredpen
      @blackpenredpen  Рік тому +4

      Thank you!

    • @Dmoney_411
      @Dmoney_411 10 місяців тому

      ​@@blackpenredpenHey I am taking AP precalculus, we are over hallways through unit 2 and it doesn't seem too bad. any suggestions on how to master my algebra (especially algebra 2) skills that are lacking from having those classes over zoom. Thank you 🙏

  • @ayssinaattori9313
    @ayssinaattori9313 Рік тому +7

    42:20 still watching, doing the questions and watching your explanation if I get stuck. Thank you for all your great videos!

  • @JonnyMath
    @JonnyMath Рік тому +5

    Hi backpenredpen!!! You always keep me motivated to record math videos!!! Sometimes I ask myself why should I continue making math videos on youtube, but then I watch one of your videos and they inspire myself to do it!!!🤗🤗🤗

  • @a.guzman1512
    @a.guzman1512 6 місяців тому +1

    What is that reference board you are using and where can I get it? Great video!

  • @sajuvasu
    @sajuvasu Рік тому +2

    Love you sir....❤️❤️❤️
    From india
    We aren't studying Trigonometry..
    But i understood all you taught....
    On the 14th question i think we can simplify it to
    Cos(x)Cos(2x)=2Cos³(x)-Cos(x)
    Its heartbreaking to see the expression being not factorised... 🤣🤣
    Any way..
    Big fan sir
    You are wonderful...🔥🔥❤️❤️
    (And Happy teacher's day also❤️)

  • @cooldown6077
    @cooldown6077 11 місяців тому +3

    Thank you so much. This will help a lot in my calculus studies. 🙂

  • @yugam6578
    @yugam6578 Рік тому +1

    Could you please make a video on jee advanced maths section

  • @samarjitdasIISERkol
    @samarjitdasIISERkol Рік тому +2

    Happy Teacher's Day Love from India ❤ 🇮🇳

  • @yoshikagekiraaaaa
    @yoshikagekiraaaaa Рік тому +2

    nice!

  • @abdirahmansamow7451
    @abdirahmansamow7451 Рік тому +3

    you are the goat, i was struggling with this topic then you popped into my recommended list and now im decent at it, thank you

  • @flazeanimations
    @flazeanimations Рік тому +1

    Idk why I always feel satisfied when he erased the whiteboard 😂

  • @sohampinemath1086
    @sohampinemath1086 Рік тому +2

    Please do 100 differential equations I need them for my exams😭😭

    • @amitlanis3104
      @amitlanis3104 Рік тому

      yesss that would be super helpful😁

    • @L17_8
      @L17_8 Рік тому +1

      Jesus loves you ❤️ please turn to him and repent before it's too late. The end times described in the Bible are already happening in the world.

    • @parv840
      @parv840 Рік тому

      12 th m h kya bhai

  • @tariqallali4507
    @tariqallali4507 Рік тому +2

    Thanks prof i really learned a bunch of things

  • @TheZerovirus1000
    @TheZerovirus1000 11 місяців тому +1

    42:39 I could watch a movie of these

  • @henridelagardere264
    @henridelagardere264 Рік тому +2

    24 Trig Problems done in *one* take, that's gotta be BPRP, aka 'The Beast'. Identity mathematics presented the way we spoilt brats have grown used to. Don't take this man for granted, though!

    • @L17_8
      @L17_8 Рік тому +1

      Jesus loves you ❤️ please turn to him and repent before it's too late. The end times described in the Bible are already happening in the world.

  • @adnantasin485
    @adnantasin485 Рік тому +2

    My interest in mathematics has grown so much because of you. You make so good content. Huge fan of your work. Thank you so much.

  • @brucefrizzell4221
    @brucefrizzell4221 5 місяців тому +1

    I pick up a lot of small details in these longer videos!

  • @anurakumara3950
    @anurakumara3950 10 місяців тому +1

    Thanks BpRp
    you're one of the great maths teacher 😎🖤❤

  • @humester
    @humester 29 днів тому

    Q13: I had 1/[(sin^2(x))(cos^2(x))]=4/[2(sin(x))(cos(x))]^2=4/[sin(2x)]^2= 4csc^2(2x). Would this be considered a correct answer?

  • @k3yb0ard73
    @k3yb0ard73 11 місяців тому +1

    I love your videos, keep up the amazing content!!! Btw, I'm in Precalculus learning Trig Identities!

  • @humester
    @humester 29 днів тому

    Q14: cosx*cos2x=cosx*(2cos^2(x)-1)=2cos^3(x)-cos(x) Is this OK?
    Setting 2cos^3(x)-cos(x)=1/2(cos(x)+cos(3x) ==> cos(3x)=4cos^3(x)-3cos(x)

  • @demiryumruk1423
    @demiryumruk1423 4 місяці тому

    for q6 an alternative solution would be to take the -1 as being equal to -sin^2(x)-cos^2(x) (multiplying original identity by -1) and substituting, then simplifying the equation down to sin^2(x)
    really helpful video, i love all your tutorials

  • @takureido3122
    @takureido3122 Рік тому +5

    Intro - 00:00
    1 - 00:51 - sinx+cotxcosx
    2 - 04:40 - (secx-cosx)/sinx
    3 - 07:16 - cotx/(cscx-sinx)
    4 - 09:00 - (1+2cosx)/(2+secx)
    5 - 10:45 - 1/(1-sinx)+1/(1+sinx)
    6 - 13:00 - (2+cot²x)/csc²x-1
    7 - 15:36 - tan(x+π/4)
    8 - 19:11 - cos(3x)
    9 - 24:09 - cos(4x)
    10 - 29:32 - sec(sin^-1x)
    11 - 32:42 - cos(2tan^-1x)
    12 - 36:56 - tan(2sin^-1x)
    13 - 42:44 - csc²x+sec²x
    14 - 45:41 - cosx cos(2x)
    15 - 49:38 - sin⁴x
    16 - 57:22 - sin⁴x-cos⁴x
    17 - 1:02:04 - tanx+tany
    18 - 1:04:47 - 2tanx/(1+tan²x)
    19 - 1:07:25 - 1/(secx-1)+1/(secx+1)
    20 - 1:12:08 - (sinx+tanx)/(1+cos(-x))
    21 - 1:16:14 - cos²x-sin⁴x sec²x
    22 - 1:14:50 - (sinx+cosx)²
    23 - 1:20:18 - sinx/(1-cotx)+cosx/(1+tanx)
    24 - 1:23:57 - sec²(x/2)

  • @seshansahoo7913
    @seshansahoo7913 Рік тому +1

    Happy Teacher's day Sir. Today 5th September every year in India we celebrate Teacher's Day to so our love toward the teachers. Your lecture are just brilliant i following your channel since 2020.thak you sir for everything.

  • @ArthurvanH0udt
    @ArthurvanH0udt 6 місяців тому

    I would love it if you’d do some extra identities for the parabolic version of trig fies. So cosp and sinp identities! Why? Cause they behave somewhat different than the normal sin/cos and hyperbolic sinh/cosh versions!

  • @crazyteamoffici7556
    @crazyteamoffici7556 Рік тому +1

    Love you sir ❤❤❤❤

  • @dannyfarias6607
    @dannyfarias6607 Рік тому +1

    Thank you so much for this amazing video

  • @gamerpedia1535
    @gamerpedia1535 Рік тому +1

    Cool thing to note:
    8cos⁴(x) - 8cos²(x) + 1 = 8sin⁴(x) - 8sin²(x) + 1

  • @demon-ow4vg
    @demon-ow4vg Рік тому

    Digamma(x)=1
    Solve this please, it's too hard
    Or explain digamma (x)=y , find x

  • @user-fh2rw9zh8g
    @user-fh2rw9zh8g Рік тому

    I didn't skip a whole 10 min ad 😂😂 hope this counts for you, because i don't have money to send

  • @nvapisces7011
    @nvapisces7011 Рік тому

    7:30 lemme just take a look at the camera (nope he is definitely taking a look at the solution jk)

  • @amarendranathhazra4142
    @amarendranathhazra4142 11 місяців тому

    Do all the 24 identities you did but hyperbolic trig instead

  • @sapoman01
    @sapoman01 2 місяці тому

    my comment down below at the 42:39 time stamp ⏯

  • @rubensf7780
    @rubensf7780 6 місяців тому

    1:03:31 Easy, cancel cos from both sides

  • @ChiefToad619
    @ChiefToad619 11 місяців тому

    I lose sleep over these videos, even though I may or may not know the content😅

  • @PIKI146
    @PIKI146 Рік тому

    I now prefer to stay home and do calculus on my weekends

  • @jitenderbajaj1808
    @jitenderbajaj1808 Рік тому

    Plz solve Integral of log base 2(x*(sin2ex))

  • @zoro8800
    @zoro8800 7 місяців тому

    these were very easy as I am in high school

  • @احمدعجينة-د2ل
    @احمدعجينة-د2ل Рік тому +1

    Master of it ❤

  • @divinitas604
    @divinitas604 Рік тому

    Where do I find the identities board?

  • @mitthrawnuruodo2880
    @mitthrawnuruodo2880 Рік тому +1

    Happy teacher's day sir🎉

  • @roof310
    @roof310 Рік тому

    can you do inequalities please

  • @n0nebtw
    @n0nebtw Рік тому

    art

  • @scottleung9587
    @scottleung9587 4 місяці тому

    Awesome job!

  • @DazHuang72
    @DazHuang72 Рік тому

    Calc 2 savior

  • @Sanatan_saarthi_1729
    @Sanatan_saarthi_1729 Рік тому

    Challenge:- solve 100 ordinary differential equations in one go,,,,next 100 partial differential equations in one go

  • @SmSitutul
    @SmSitutul Рік тому

    broo ❤❤

  • @ITWorksSoftware
    @ITWorksSoftware 9 місяців тому

    42:40 yes, doing it with you. I've also done the 100 derivatives twice now, and the 100 algebra twice, too... Great practice!

  • @RishavPlayz2007
    @RishavPlayz2007 11 місяців тому

    42:40 yes i am following along solving all the questions, they're pretty easy, excited for the upcoming questions

  • @davidthomas6043
    @davidthomas6043 Рік тому +1

    I don't understand why he puts cos3x = (cosx)(cos2x)..This seems wrong, because for example, cos 60 = o.5, but cos 20 is .9397 and cos 40 is .766, and multiplying these these gives an answer of of .7198. which is nowhere near .5 ! Can someone please explain? I Thanks

    • @AttyPatty3
      @AttyPatty3 Рік тому

      Hey David! He didn't put cos 3x = (cosx) (cos2x) instead what he did was simply write the 3x as 2x + x. cos(3x) = cos(2x + x)

    • @davidthomas6043
      @davidthomas6043 Рік тому

      Thanks for answering. I now see that what he wrote was (cos x)(cos2x- minus (sin x)(sin 2x). Silly me !! @@AttyPatty3

    • @davidthomas6043
      @davidthomas6043 Рік тому

      Further to mt previous reply, can you please tell me if there is any way available to derive the formula cos (A + B) = cos A.cos B - sin A.sin B ?@@AttyPatty3

  • @franciscomorales8102
    @franciscomorales8102 3 місяці тому

    My Lord!!! Thank you very much!!! You had simplified my life!! I’m back in school after many years, and I was struggling into I found your video!!!
    Where did you got the T-shirt and the table you have on the wall???
    I appreciate your time, dedication and advice!!!

  • @salvadorsabateromero2258
    @salvadorsabateromero2258 10 місяців тому

    18:55

  • @Bambambami
    @Bambambami 9 місяців тому

    This is driving me crazy i wanna cry so bad

  • @thenew3dworldfan
    @thenew3dworldfan Рік тому

    I have a question. Suppose a(n) is the integer sequence A007916. Does the series (1 to inf) 1/ (A007916(n))^2 conv or div?

  • @frozenpeak1524
    @frozenpeak1524 11 місяців тому

    I'm taking AP Precalculus this year and so far its not bad. So far its just been obtaining a deeper understanding of functions and what values can be obtained from the equation of a function.

  • @user-fh2rw9zh8g
    @user-fh2rw9zh8g Рік тому

    Hello!! I've just finished watching 50 integrals video, and I'm so happy to see this as I'm struggling with trigonometry!

  • @foolwhodreams
    @foolwhodreams Рік тому

    thank u for this. i took ap calculus bc and skipped calc 1 and 2, and im scared of trig identities coming up in chapter 12 for calculus 3 !! big fan

  • @TanmaY_TalK
    @TanmaY_TalK Рік тому

    Do a 100 question One Shot version and put in 100 question playlist

  • @walter9029
    @walter9029 Рік тому

    Is ex. 2 an identity? Because in the original fraction all values equal to kxpi are not in the domain.

  • @illumexhisoka6181
    @illumexhisoka6181 Рік тому

    7 can be simplified to tan(2x)+sec(2x)
    and 13 can be 4sec^2(2x)

  • @themultiroundergamer6073
    @themultiroundergamer6073 Рік тому

    hey whats that black identity board you have hanging beside the whiteboard? is it available online?

  • @wearealiens2050
    @wearealiens2050 Рік тому

    😂Imagine, sir, that you unplug the camera lol

  • @stavzee
    @stavzee 10 місяців тому

    His smile just makes me wanna study more

  • @datarioplays
    @datarioplays Рік тому

    Do more integral battles between elementary and non-elementary ones! The one you did 4 years ago wasn’t enough for me.

  • @kirbo722
    @kirbo722 Рік тому

    This video was VERY helpful, thank you!!

  • @wearealiens2050
    @wearealiens2050 Рік тому

    I have an equation who solves it ‏‪13:19‬‏

  • @Jeepreparation-z9n
    @Jeepreparation-z9n Рік тому

    Hey man you are really an inspiration for me.your passion keeps me motivated ❤

  • @lgooch
    @lgooch Рік тому

    Do inverse trig identities next!