Verifying Trigonometric Identities

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  • Опубліковано 19 чер 2024
  • Verifying trigonometric identities can be super fun! And also very frustrating when you can't figure them out. It can be tricky because there's no precise way to go about doing this, you have to just use your intuition, but let's go over some common strategies and identities that will more than likely use at one point or another!
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КОМЕНТАРІ • 183

  • @zekenazari6781
    @zekenazari6781 5 років тому +218

    "how about one more since these are so fun" Dead

  • @heavenlee4466
    @heavenlee4466 5 років тому +599

    I’m about to fail tf out this test....

  • @johnpringle9967
    @johnpringle9967 5 років тому +192

    "Quite infuriating"? Man, you said it! I am a retired electrician who washed out of civil engineering because of calculus and specifically, trig identities. To this day, I have math books beside my bed, in the bathroom, in my car, etc. I really would like to get a grip on this stuff and it has turned into a kind of grudge match between the math and my little brain. I found your video very well presented -- not some guy scribbling illegibly at warp factor 9 -- and the content moves along at a rate where even an idiot like me can pause the screen and work through the material to catch up to you. Well done!

    • @DevDevi
      @DevDevi 3 роки тому +5

      You are describing me. 😂👍

  • @Tom-xy9gb
    @Tom-xy9gb 7 місяців тому +9

    Video after video. Lesson after lesson. I could never understand what I was supposed to do. Until I watched your video. So simplistic and not a bunch of writing and lots of talking. Straight to the point. Thank you!

  • @reveinluv8759
    @reveinluv8759 4 роки тому +15

    "since these are just so fun," says it so unenthusiastically. but on a serious note, this really helped

  • @Fayemid
    @Fayemid 3 роки тому +16

    10 minutes before my test: well idk what im doing

  • @ddrum121
    @ddrum121 4 роки тому +8

    Thank you Prof Dave, came here cause I wasn't sure what to do when some terms are squared and some aren't. This stuff is pretty satisfying to solve

  • @tyfoodsforthought
    @tyfoodsforthought 3 роки тому +36

    I haven't done this stuff in about 3 years. I very much remember this as being THE worst part of trig. I practically experienced flashbacks attempting these again. 😂
    Anyway, love this entire series. It's an excellent refresher, and very well put together! Thank you!

    • @levishhunted7593
      @levishhunted7593 3 роки тому +1

      ifkr! bruh i know absolutely everything else in like the entirety of math except this shit

  • @EE-jn8ku
    @EE-jn8ku 3 роки тому +1

    Thanks. My algebra 2 teacher glossed over the 3 basic identities so I couldn't really understand it. This video helped me more than 3 of her in class periods. Thanks!

  • @sherasantiago6026
    @sherasantiago6026 5 років тому +8

    You're a great teacher! Thank you so much, your video helped me a lot to understand this lesson. I hope that you'll continue to make videos on solving mathematical problems. 😊

  • @naveensundar4765
    @naveensundar4765 3 роки тому +1

    Thanks! You made this extremely easy!

  • @TheSpasmer
    @TheSpasmer 4 роки тому +1

    you make it look so easy.thank you prf.dave

  • @jorgetejeda6058
    @jorgetejeda6058 6 років тому +3

    This video helped me a lot. Thx

  • @altoclef4989
    @altoclef4989 4 роки тому +12

    Thank you Professor Dave-- I used to think these were so frustrating, but now I think they're beautiful :)

  • @TheGamingInkling
    @TheGamingInkling 2 роки тому +8

    This cleared up quite a bit of questions! Can't ask questions in class not because my teacher doesnt let us, but because I don't like to hold the class back by asking questions to problems I should have figured out days ago

  • @giftkikuyo3551
    @giftkikuyo3551 6 років тому +1

    you are my hero!
    Genius Dave

  • @nanisesauma2106
    @nanisesauma2106 2 роки тому +1

    Thank u so much it helps me a lot in my trigonometry

  • @burneracc1366
    @burneracc1366 2 роки тому +4

    let's do another because they are so fun! after that sentence i burst out laughing because i found it insanely ironic, made my day 10/10 even if it wasn't a joke

  • @SilentKiller-yn4jo
    @SilentKiller-yn4jo 6 років тому +26

    Wish I had seen this last year. But now I still struggle with trig because of the new formulas like sin (x+y) and all those double and half angle formulas. Its been bothering me for a while and my boards are coming up. So, professor, can your next video be related to advanced trig functions. My notifications are on so I get informed everytime you upload. Thanks in advance

  • @goldenbeard150memes3
    @goldenbeard150memes3 3 роки тому +3

    Dave Grohl is helping me pass my midterm. Thanks!

  • @eshanika549
    @eshanika549 Рік тому +3

    0:03 i seriously love this part 🤣🤣🤣
    now I'm a bit confident abt trigonometry..........thanks, professor!!!

  • @nikhilparkash4924
    @nikhilparkash4924 2 роки тому

    Thanks professor Dave ldk what to do but u made it simple

  • @thaihm
    @thaihm 5 років тому

    Simply amazing. I love how you lecture and utilize graphics, thank you, Prof. Dave!

  • @user-hm5pb1ms4d
    @user-hm5pb1ms4d 9 місяців тому

    Thank you Professor

  • @Nigel-wz8hb
    @Nigel-wz8hb 5 років тому +2

    Professor Dave, I would like to know why is Trigonometry so hard; even through you have look at the same series of problems for days?

  • @armybros8379
    @armybros8379 6 років тому +2

    Thanks this made me feel better after my test.

  • @skysick6922
    @skysick6922 4 роки тому

    He explains it very well

  • @mauriciovega957
    @mauriciovega957 5 років тому +1

    Probably one of the best intros in the history of intros

  • @amritakoirala3087
    @amritakoirala3087 6 років тому +2

    You are right . .......Please do logarithmic derivatives

  • @Drforeverok
    @Drforeverok Рік тому

    Excellent video

  • @SquarePupilIndustr
    @SquarePupilIndustr 5 років тому +2

    at 2:30 dont you have to multiply both sides by cos/cos. what rule says you can selectively manipulate on part like that?

  • @kimjungyun1195
    @kimjungyun1195 6 років тому +11

    Professor dave, I have watched all your educational videos and i affirm that your videos are much useful & informative but problem is that you have uploaded less video concerning math...
    I request please upload plenty of math lessons...

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  6 років тому +11

      buddy i upload two maths a week! don't worry, you will get all of your math. i'm shooting more next week.

    • @hasanojan5570
      @hasanojan5570 2 роки тому

      @@ProfessorDaveExplains
      I don't know if you make videos about calculus or not but it would be of great help for me cuz I suck at calculus

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  2 роки тому

      I have a 35 part series on calculus, check it out!

  • @zakirmohammed9662
    @zakirmohammed9662 6 років тому +2

    Plz prof Dave prepare us the concept of mirage of total internal reflection I haven't enough idea tnx

  • @jean-5633
    @jean-5633 5 років тому +1

    Thanks for everything I have a question where did you get the 1 how did it change by sine on the second exercise,the one in the middle bottom

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  5 років тому +1

      sorry i'm not sure what you're referring to.

    • @jean-5633
      @jean-5633 5 років тому +1

      @@ProfessorDaveExplains on checking comprehension. I didn't understand the one in the middle in where you replace the - sine by 1

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  5 років тому +1

      ah i see, so i factored sinx out of that difference.

  • @jessicamateo-lorenzo748
    @jessicamateo-lorenzo748 4 роки тому +1

    Thank you so much for this video!!! you're helping me understand trig identities much better than my teacher.

  • @windthugness
    @windthugness 2 роки тому +1

    Where does this other cosx come from?

  • @sheryachand377
    @sheryachand377 2 роки тому

    thanks

  • @rosemariedelossantos1497
    @rosemariedelossantos1497 2 роки тому +1

    Imagine the world without this man😂

  • @matiasjacobsen2647
    @matiasjacobsen2647 5 років тому

    awesome video

  • @surajsonkar8734
    @surajsonkar8734 5 років тому

    Sir doubt at 5:35 ,we can take lcm also but why we have not taken ? And how to know

    • @prasoonjha1816
      @prasoonjha1816 2 роки тому

      We can do that as well, in fact my school teacher did took LCM for this identity but this way is a lot quicker than that one.

  • @Billsomebody89
    @Billsomebody89 8 місяців тому

    I like the subtle comprehension tests. Sadly, i can't seem to comprehend the majority of this chapter. A bit frustrating seeing how important this is for calculus. I think im having such trouble because its highly focused on vocabulary turned equation. Im pretty sure my left temporal lobectamy amplifies the difficultly. Seeing as how that is where we keep our vocabulary.

  • @thvtsydneylyf3th077
    @thvtsydneylyf3th077 4 роки тому

    cheers professor ur like some god of maths or something, ty

  • @gabrielcx16
    @gabrielcx16 3 роки тому

    Is that a rule of trig when you multiplied cosx times cosx/cosx? Are you allowed to pull out that fraction when necessary?

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  3 роки тому +1

      well you can always multiply anything by 1

    • @gabrielcx16
      @gabrielcx16 3 роки тому +1

      @@ProfessorDaveExplains ohhhhh I see how cosx/cosx= 1, in that case yea I see how you can multiply anything by 1. Thank you a lot

  • @hanasiyum2879
    @hanasiyum2879 2 роки тому

    Thanks it is cool

  • @Exonorm27
    @Exonorm27 2 роки тому +5

    I’m probably weird for this, but I loved this part of Trigonometry. Everything else in trig was boring, or irritating but this was actually really fun 😂

    • @vanitas5097
      @vanitas5097 9 місяців тому +1

      yes indeed u are weird... proving geometry is easier than this for me

  • @reinazushi
    @reinazushi 5 років тому +2

    thank you so much for helping me with my stupid math homework ahhhhhh!!!!!

  • @namp2018
    @namp2018 Рік тому +1

    in the checking comprehesion section, the last equation went from
    sin x - (sin x)(cos² x)
    to sin x - (1 - cos² x)
    may I ask how and why?

    • @cherrynuht
      @cherrynuht Рік тому

      sorry for the late response to this comment!!!!!! what he did was factor out what both sides of the subtraction side had, being the sinx, that is why there is now a 1 as well. This makes it easier to turn the (1-cos^2x) into the sin^2x

    • @jeanne5067
      @jeanne5067 9 місяців тому

      ​@@cherrynuhtHi, I am struggling with that question too, would that be possible for you to write it down because I still don't understand?
      sin x - sin x cos^2x =
      sin x/sinx - sinx/sinx • cos^2x ??

    • @heliomiranda9622
      @heliomiranda9622 8 місяців тому +1

      This is because if you calculate [sin(x)(1 - cos^2(x))] you will get exactly [sin(x) - sin(x)cos^2(x)]... then it is just a different way (though factor out both sin(x)) to represent the same thing... but now it will have the [1 - cos^2(x)] which can be converted to [sin^2(x)] that multiplied by the remaining [sin(x)] will give [sin^3(x)] on the left side. To end: [sin^3(x) = sin^3(x)]. It is the same as [a - ax] => a(1 - x).

  • @user-hv6ef9ie1g
    @user-hv6ef9ie1g 5 місяців тому

    5:30 Aren't we supposed to multiply both sides of the equation by 1-sin x/1-sinx? or am i missing something here?

    • @egonspenglercore
      @egonspenglercore 4 місяці тому +1

      I think it's because anything over itself is 1, so he doesn't show it because it's just saying 2secx(1), and (1-sinx)/(1-sinx)=1

  • @DanielS-ev3fm
    @DanielS-ev3fm 5 років тому +14

    I literally have finals tmr I'm hopeing I'll get Tru this

  • @woogieboogie1000
    @woogieboogie1000 3 роки тому

    I thought when you multiply fractions you have to take the reciprocal of tan x. So wouldn’t that be cos x over sin x ?

  • @adweita990
    @adweita990 5 місяців тому

    i was terrible at this in 10th grade. now in 12th- i have been academically inactive for 2 years and i got these in one go. maybe it was just the way it was taught and mindfulness back then!

  • @blessedkutsirayi9262
    @blessedkutsirayi9262 4 роки тому

    Now I'm ready for my test tomorrow

  • @46-firozc73
    @46-firozc73 5 років тому

    Sir instead of using trig formula to solve the problem can we use this strategy? Pls reply

  • @iprovedthem5527
    @iprovedthem5527 2 роки тому

    Since the video is a little old, you may not see this, but on the second example where you said multiplying cos x by cos x/cos x seemed arbitrary it looks more like cheating to make the process work. I'm 20 years out of school working through a trig unit for a home learning course so I can go to University and I see a lot of this kind of thing in my course material and none of it gets explained. How is it that you can do that without multiplying the other side of the equation as well? I know I probably look super dumb right now, but Maths is hard!

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  2 роки тому +2

      You can multiply anything by 1 without changing its value, and anything over itself equals one.

    • @iprovedthem5527
      @iprovedthem5527 2 роки тому

      @@ProfessorDaveExplains Wow, that was fast. Thank you and I now feel super dumb because that is so obvious.💪🧠

  • @kavyamorya1258
    @kavyamorya1258 5 років тому +2

    I wish u were there when I was in 10th std.trignometry was my nightmare.But it's kk I still need them.

  • @cubixmem
    @cubixmem Рік тому +1

    With this video, I ain't failing the test no more

  • @manusaini13
    @manusaini13 5 років тому +2

    7:59

  • @silvershard8009
    @silvershard8009 Рік тому

    At least a thousand times better than my Math teacher and he did it in minutes

  • @tGoldenPhoenix
    @tGoldenPhoenix 2 роки тому

    Done.

  • @jorgecapitao1435
    @jorgecapitao1435 Рік тому +1

    I LOOOOOVE YOU FOR GOD SAKE THANK YOU SO MUCH YOU SAVED ME FROM MY USELESS TEACHER

  • @littleretroship6403
    @littleretroship6403 2 роки тому

    Man! There are so many relations between the different functions.

  • @holyshit922
    @holyshit922 3 роки тому

    Is it really true ? What about x = kπ , where k in Z

  • @anchoi3662
    @anchoi3662 2 місяці тому

    I'm not all the way there yet but at least I'm not just staring at the paper anymore so thank you 🙏

  • @lovemorejunior4304
    @lovemorejunior4304 5 років тому

    i like the tutorial

  • @spica3132
    @spica3132 2 роки тому

    thaaaank yoooouuuu veeerryyyy muuuccccchhh!

  • @Duck-wb8rf
    @Duck-wb8rf 6 років тому +2

    Wow, you know a lot about all kinds of stuff, KONNOO DIIOO DAA!!!!, understands.

  • @user-jj4zb5jd6r
    @user-jj4zb5jd6r 5 років тому +2

    You will never understand how much your videos have helped me, you’ve literally saved me from killing myself

  • @khconlineeducation
    @khconlineeducation 5 років тому

    👍👍👍👍👍👍👍👍

  • @SuperMan-uj7dh
    @SuperMan-uj7dh 6 років тому

    Hi professor!

  • @chokelit4148
    @chokelit4148 4 роки тому +4

    Im failed many times but im never give up then my 3rd try its correct

  • @harrisonkrieger7029
    @harrisonkrieger7029 5 років тому

    @3:43 -- isn't that a Pythagorean Identity in and of itself?

  • @user-pz5di2gk6v
    @user-pz5di2gk6v 4 роки тому

    It looks so easy now

  • @elrinesporlas296
    @elrinesporlas296 4 роки тому +2

    Farquad be teaching math now

  • @Kim-mq1qm
    @Kim-mq1qm 2 роки тому

    2:57

  • @haimharar6741
    @haimharar6741 2 роки тому

    in the third question in the comprehension it need to be a plus rather than minus i think

  • @ambulance2793
    @ambulance2793 6 років тому +20

    Even Speedwagon understands.

    • @ivoryas1696
      @ivoryas1696 2 роки тому +1

      Ambulance
      He does?
      *_Niiiiiiiiiceu_*

  • @lalmuanpuii7190
    @lalmuanpuii7190 Рік тому +1

    this is class 10 level right? i was searching for class 12 🥲

  • @Yui_Fukushima0104
    @Yui_Fukushima0104 6 років тому +6

    Goddamit this. Trig identities is the hell of my life

  • @eddyrajan3523
    @eddyrajan3523 4 роки тому

    There’s one thats like TanA= secA/cscA
    Help?😞

  • @adolfocarrillo248
    @adolfocarrillo248 5 років тому

    In min 6:10 Why "2 sec X = 2 / cos X"

  • @champsinger
    @champsinger 7 місяців тому

    Ez

  • @1emnL
    @1emnL 3 роки тому

    watching this right before my test pls pray for me

  • @clive_clive
    @clive_clive 5 років тому +8

    too sleepy to learn

  • @mypenisisincrediblysmallbu5538
    @mypenisisincrediblysmallbu5538 3 роки тому +1

    did anyone elses teacher tell them to strictly change one side only?

  • @imj9581
    @imj9581 6 років тому +3

    6:17 "since these are just 'sooo' fun"
    why does it sound like even he is admitting these are not fun XD

  • @Pngmade675
    @Pngmade675 2 роки тому

    I find the writings highlighted in black quite irritating

  • @josephshim2442
    @josephshim2442 4 роки тому

    I dig the chest hair

  • @karlkrueger3142
    @karlkrueger3142 5 років тому

    Found the content helpful, but it didn't really help me with the practice problems at the end.

  • @Displ4c
    @Displ4c 4 роки тому +1

    I’m not very smart so this is hard asf

  • @phoebe7918
    @phoebe7918 3 роки тому

    That easiest questions I never see on tri ident...

  • @ahmadyasin257
    @ahmadyasin257 4 роки тому

    How many of you all just see the working and don't do them themselves....ha ha ah ah a..Welcome to the group...

  • @Kurt4014
    @Kurt4014 28 днів тому

    Bagsak nako bukas

  • @isaacgordon6259
    @isaacgordon6259 3 роки тому

    It made sense up until the second example...imma fail this test

  • @donutthephuan7231
    @donutthephuan7231 4 роки тому

    Anybody else stuck doing trig in quarantine?

  • @masauso8523
    @masauso8523 2 роки тому

    Jesus has saved my CA again 👏👏👏

  • @ouma2368
    @ouma2368 2 роки тому

    for 10 points :>

  • @connerskyes2748
    @connerskyes2748 4 роки тому +1

    Reveal your ethnicity, Professor Dave! You look like a Cuban Einstein.

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  4 роки тому +1

      haha that's a new one! check out "ask professor dave #1"

    • @connerskyes2748
      @connerskyes2748 4 роки тому

      Professor Dave Explains I will! I can’t believe I received such a timely response. You’re the reason I have a 105% in Pre-Calculus.

  • @al.s.3277
    @al.s.3277 6 років тому

    Yeah I’m gonna Gail tomorrow’s exam

    • @MrPeach-fs9kn
      @MrPeach-fs9kn 5 років тому

      Just like how you failed to spell fail. Jk.

  • @vanessah4943
    @vanessah4943 4 роки тому

    Why do I have to know this...ugh

  • @Joseph-bd3pk
    @Joseph-bd3pk 5 років тому

    Ahhhhh I hate this lesson so much