Double Angle Identities & Formulas of Sin, Cos & Tan - Trigonometry

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  • Опубліковано 20 січ 2025

КОМЕНТАРІ • 212

  • @TheOrganicChemistryTutor
    @TheOrganicChemistryTutor  Рік тому +10

    Trigonometry - Free Formula Sheet: bit.ly/47diggI
    Trigonometry Video Lessons: www.video-tutor.net/trigonometric-identities.html

  • @DemonCoreEntertainment
    @DemonCoreEntertainment Рік тому +94

    I’m so happy I found your channel. You are helping me to understand the subject better and save my grade one vid at a time!

  • @jorgeleiva8374
    @jorgeleiva8374 4 роки тому +415

    Omggg you explained better in 5 minutes what my teacher couldn't in 2 hours. Thank you so much!

  • @marinadamato9043
    @marinadamato9043 3 роки тому +80

    the fact that I learned a whole weeks worth of lessons in 10 minutes really says something. You are the absolute best my friend!

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    @bryanmayodi613 3 роки тому +60

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  • @lucidfangirl1030
    @lucidfangirl1030 4 роки тому +437

    What to do when UA-cam teaches you better than the *pre-recorded* videos on your *school's* website: 🤨

  • @jn4198
    @jn4198 4 роки тому +69

    I allways struggle with the Tangent equation, but the way you showed it, its so clear.

  • @bricali
    @bricali Рік тому +5

    Youve helped me throughout the years, really wanted to thank you for posting these videos you have no idea how many lives you change

  • @georgesadler7830
    @georgesadler7830 3 роки тому +18

    MR. Organic Chemistry Tutor, thank you for a fantastic video on Double Angles Identities and Formulas of Sine, Cosine and Tangent.

  • @danellespalla8697
    @danellespalla8697 5 років тому +48

    Your content is amazing! And sooo sooo sooo helpful!

  • @melo.024
    @melo.024 11 місяців тому +1

    I had many tabs open explaining the same concept just in case I did not follow along well with the teaching, but I didnt need to choose another video... this one was it

  • @alster724
    @alster724 2 роки тому +23

    For cos 2x there are 3 possible formulae
    1.) cos 2x = cos²x-sin²x
    The next two are obtained from Pythagorean Identities
    First cos²x = 1-sin²x
    cos 2x= 1-sin²x-sin²x
    2.) cos 2x = 1-2sin²x
    And also sin²x= 1-cos²x
    Reverting to the first formula and substitution we get
    cos 2x = cos²x-(1-cos²x)
    We finally have
    3.) cos 2x = 2cos²x-1

  • @morganriddiford2646
    @morganriddiford2646 6 років тому +28

    why are you better than my last 4 teachers combined ( my whole of highschool math)

  • @kylesislak9460
    @kylesislak9460 2 роки тому +5

    Great video! Very helpful!! Will definitly be subscribing for more help in the future! Keep teaching the way you do its amazing and better than any professor who cant ctrl+Z or use shortcut commands! Very swift and efficient!

  • @emwaleed08
    @emwaleed08 2 роки тому +7

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    @tena1486 2 роки тому +1

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  • @FooartByStewart
    @FooartByStewart 8 місяців тому +1

    I was so afraid I would not understand how to do this. I kept telling myself nothing is impossible! I watch your videos and feel like I can learn even the most confusing topics. My teachers are no help of showing how they got an answer- they only show the answers. Thank you for making this so simple to understand!

  • @bobjones1999
    @bobjones1999 5 місяців тому

    Thank you so much!! I was staring at my textbook for like a half an hour straight and literally none of the words didn't make sense. I didn't realize it was this simple all along!

  • @dayungdon8725
    @dayungdon8725 6 років тому +44

    This helped a lot! I got a quiz on this right now 😨

  • @CKDesigner2525
    @CKDesigner2525 Рік тому +2

    I like the cool way you used to prove the double angle identities, thank you!

  • @MM-dj2cv
    @MM-dj2cv 2 роки тому +1

    REALLY YOU ARE THE BEST NEVER SEEN OVER THIS WORLD. IAM FROM SOMALIA THANK YOU

  • @Agoobernamedseth
    @Agoobernamedseth 3 роки тому +7

    This really helped me with double angles, thank you so much 🙏

  • @philasandevennessa2988
    @philasandevennessa2988 Рік тому +3

    U explained this in a space of 3 minutes and I understood unlike my teacher who had to stand in front of me for 2 hours but no understanding ❤️

  • @Talhaaden
    @Talhaaden 4 місяці тому +1

    Complete Formula;
    for sine - 0:51
    for cosine - 1:51
    for tagent -2:51

  • @Bambambami
    @Bambambami Рік тому

    I just want u to know that an angel is born everytime u post

  • @sarahchasauce935
    @sarahchasauce935 2 роки тому +2

    I love watching it get proven so swiftly thanks

  • @roofie4622
    @roofie4622 2 роки тому +4

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  • @quinruizjr.8654
    @quinruizjr.8654 2 роки тому +2

    Thank you so much.
    Your videos really helped me a lot.
    It was easy to understand

  • @alyrainnee4939
    @alyrainnee4939 Рік тому

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  • @soulsidewest
    @soulsidewest 2 місяці тому

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  • @mingyuez5614
    @mingyuez5614 4 роки тому +4

    holy-- i love u so much thanks for helping me in math TT

  • @shaynerushton214
    @shaynerushton214 3 роки тому +27

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  • @hamzamemon1668
    @hamzamemon1668 Місяць тому +1

    Nicee explanation !

  • @ducklund8578
    @ducklund8578 4 роки тому +9

    And this, ladies and gentemen, why online education is better than classroom education

  • @noelwanda4484
    @noelwanda4484 2 роки тому

    Probably your are the best sir you know how to simplify things in your explanations

  • @jamesfay6234
    @jamesfay6234 4 місяці тому

    @TheOrganicChemistryTutor
    @8:10 why did you multiply the numerator and denominator by 16 instead of creating common denominators and multiply by the reciprocal? I fully understand that your method is valid and a slightly different approach, I've just never taught it this way.

  • @MewdedTatek
    @MewdedTatek 9 місяців тому +1

    Great teacher . thanks ❤

  • @shahdmohamed5314
    @shahdmohamed5314 3 роки тому +4

    جزاك الله خيرا
    Thank you

  • @t.zebary9822
    @t.zebary9822 3 роки тому

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  • @divineanyanechi6928
    @divineanyanechi6928 3 роки тому +1

    Wow this is a very nice explanation am so grateful bro

  • @jayeshjadhav6290
    @jayeshjadhav6290 3 роки тому +1

    that was very easy to understand bruh... thanks

  • @aryanahm.4086
    @aryanahm.4086 Рік тому

    Bro that makes so much sense thank Goodness for youtube and you cuz I was so confused 😂

  • @latifaalrajhi3255
    @latifaalrajhi3255 2 роки тому +2

    3:54 how did you get the 4?

  • @reidcipriani5673
    @reidcipriani5673 3 роки тому +1

    Another great video, thanks for posting

  • @MimmyBliss
    @MimmyBliss Рік тому

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  • @mr.moon17
    @mr.moon17 4 місяці тому

    thank you so much!💛

  • @AbdullahHaque-wk8kb
    @AbdullahHaque-wk8kb 10 місяців тому

    Your channel is like thesaurus for maths. Whenever I don't understand sth, i look that up here.

  • @skullrhino2564
    @skullrhino2564 4 роки тому +1

    Love watching your videos

  • @RachidKoné-m7n
    @RachidKoné-m7n Рік тому +2

    Thank you, now I understand better
    I will sleep less stupid

  • @buddy7638
    @buddy7638 2 роки тому +1

    This guy literally teaches better than my school right now

  • @St.Raptor
    @St.Raptor Рік тому

    The fact this man has saved so many grades and helped so many people without even being in person is proof our current education system sucks worse than a random dude on UA-cam.

  • @adatdz5011
    @adatdz5011 2 місяці тому

    dude you're the best

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    @sanopann1896 Рік тому

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  • @cproteus
    @cproteus 6 років тому +1

    What would be so awesome, for people like me is if you could rewind in 15 second increments. Is that a feature you can turn on? I see it in some videos, and it’s good when I go, what was that again...? My big finger goes back minutes not the thing you just said. Your videos are an inspiration, thank you So Much!

    • @meltedcow9672
      @meltedcow9672 3 роки тому +4

      i'm 2 years late but in case anyone is wondering, pressing the left arrow will rewind a video by 10 seconds

  • @fatimahjanjua6915
    @fatimahjanjua6915 9 місяців тому +1

    May God bless you!

  • @anorttn4718
    @anorttn4718 Рік тому

    Thank you for saving me from my math tutorial class.

  • @joemarsuson4095
    @joemarsuson4095 Рік тому +1

    thank you po

  • @Uccntt
    @Uccntt Рік тому

    Thx a lot I don’t know how to thank u U R amazing 💋💋

  • @innovativemindstutor
    @innovativemindstutor 4 роки тому

    Best tutor well explained

  • @AmberRathour366
    @AmberRathour366 3 роки тому +1

    At 9:43
    Why isn't the hypotenuse negative?

    • @supremechair5812
      @supremechair5812 3 роки тому +4

      The hypotenuse is positive no matter which quadrant it is in.

  • @Rose-hq5zk
    @Rose-hq5zk Рік тому

    how tan could be positive while theta is in q4? 12:56

  • @Nemoguzapomnit
    @Nemoguzapomnit 6 років тому +6

  • @himanshubarnwal934
    @himanshubarnwal934 Рік тому

    Big help sir🙏🏻

  • @alster724
    @alster724 4 роки тому +9

    The sin 2x/cos 2x is the best trick for tan 2x

    • @julietokonko4274
      @julietokonko4274 4 роки тому +6

      Are you a mind reader because I said that exact thing in class and my teacher gave me bonus points for finding a simpler way.

    • @humphreybwalya4854
      @humphreybwalya4854 3 роки тому +1

      Same in mind as well

    • @alster724
      @alster724 2 роки тому

      @@julietokonko4274 My Senior High Math Doctor taught me this trick

  • @likagogodze9951
    @likagogodze9951 3 роки тому

    Thanks for helping.

  • @joshchukwu4351
    @joshchukwu4351 2 роки тому

    Bro u are a magician 😂😂😂😂😂😂I swr how did I understand this soooo fast

  • @ilanmusk3503
    @ilanmusk3503 2 роки тому +3

    how do you know what type of triangle you have?

    • @ilhamo_3427
      @ilhamo_3427 2 роки тому +2

      theres only 2 triangles, the first one has two 45 degrees and one that is 90 degrees. and the other one has 60 and 30 degrees and one 90 degrees.
      so in conclusion there's onyl 3 angles that you can only use when finding the exact value of any of the trigonometric ratios. you cannot write any other angle.
      OR..
      you can just skip the special triangles and type the trigonometric ratio with its angle on the calculator and you'll get the exact value with that. one thing to keep in mind is if the answer was √a/a on the calculator you write 1/√a instead.
      FOR EXAMPLE;
      tan(30) = √3/3 *on calculator*
      but if you use the special triangle you will get 1/√3.
      hope that made sense.

  • @joshuabacchus4426
    @joshuabacchus4426 5 років тому +3

    How do u know which quadrant the angles fall in... I don't know how to tell.

    • @d8264
      @d8264 5 років тому

      Compare angles to unit circle.

    • @Meggutz
      @Meggutz 5 років тому +9

      Joshua Bacchus
      Pi is equal to 180
      Quadrant 1 - 0 to 90
      Quadrant 2 - 90 to 180
      Quadrant 3 - 180 to 270
      Quadrant 4 - 270 to 360

    • @adriangutierrez2229
      @adriangutierrez2229 3 роки тому

      @@Meggutz this was very useful thx

  • @saintsour124
    @saintsour124 3 роки тому +1

    why even go to class if I can just watch your vids and understand in literally 1/4th the time

  • @antertoby5406
    @antertoby5406 6 років тому +2

    you are my best mathematics teacter

    • @matthewreddy2841
      @matthewreddy2841 6 років тому +5

      Yeah you need a better English teacher my dude🤣

  • @gabyzamora5297
    @gabyzamora5297 Рік тому

    THANK YOU

  • @tiffanyodimegwu2168
    @tiffanyodimegwu2168 3 роки тому

    ❤️❤️❤️THANK YOU

  • @liwiikiwii
    @liwiikiwii Рік тому

    how can you determine the type of triangle that it is?

  • @innocentmunama.5366
    @innocentmunama.5366 11 місяців тому

    You just saved me dude, 🎉... Couldn't get this in class yapa Luanar (Bunda campus)

  • @QuangNguyen-dw9je
    @QuangNguyen-dw9je 3 роки тому +2

    0:07 No I don't remember that equation

  • @Buddhabebop
    @Buddhabebop 2 місяці тому

    why isnt the hypotenuse of the 5-12-13 triangle at 10 minutes negative? its in the 4th quadrant after all

  • @jaychoro8159
    @jaychoro8159 3 роки тому +1

    Why isn't Cosine positive since its in quadrant 4?

  • @breeelam2280
    @breeelam2280 3 роки тому +5

    Our teacher asked us to work the problem out in bold on paper and hold it up. I scribbled organic chemistry tutor as legible as possible and held it up.

  • @matts8791
    @matts8791 2 роки тому

    Organic Chemistry Teacher is literally superior to my teacher.

  • @brojers1603
    @brojers1603 3 роки тому +2

    My only problem is finding this out right at night before the test 😩

  • @qquamau7
    @qquamau7 2 роки тому +1

    someone please tell me why only the 12 was negative in the fourth quad while 5 and 12 were exempted

  • @nuwangiliyanage1166
    @nuwangiliyanage1166 3 роки тому

    thank youuuuu

  • @أبوصالحالمطوع
    @أبوصالحالمطوع Рік тому

    That was greaaaaaaaaat!

  • @boostaddict_
    @boostaddict_ 2 роки тому

    So these videos are great and all but one of the questions I'm having to answer, is simplifying 6 sin 5x cos 5x. Would the sin 5x be 5 sin theta cos theta, instead of 2? I have 0 ideas for how to do the cos 5x lol. Maybe 5 cos^2 theta - 1?

    • @boostaddict_
      @boostaddict_ 2 роки тому

      nope, just realized it was a multiple of sin 2x lmao. It's 3 sin 10x.

  • @patriceestacio3650
    @patriceestacio3650 4 роки тому

    Thank you thank you thank you

  • @KyoungwooBae-ni4yu
    @KyoungwooBae-ni4yu Рік тому

    how do i do stuff like cos112.5 in angles?

  • @tobiasmekpee8568
    @tobiasmekpee8568 2 роки тому

    What if there is a question that requires the answer like if there is given (sin tita=3/5) and (cos tita - 4/5).The cos2tita =7/25...my question is how can we make reciprical to find its (sin tita=3/5)and (cos tita - 4/5)..please help me..

    • @ilhamo_3427
      @ilhamo_3427 2 роки тому

      whats the question exactly?

  • @tabiosmariojr.6412
    @tabiosmariojr.6412 Рік тому

    what if the question is secant, cosecant and cotangent

  • @jrzzyplayz8692
    @jrzzyplayz8692 2 місяці тому

    Is this further maths only

  • @SDILUYNTsiu39fnd
    @SDILUYNTsiu39fnd 2 роки тому

    5:59. that 5 tho 😂

  • @mikengaaisha3187
    @mikengaaisha3187 2 роки тому

    Sir so not understood where the 4 comes from

  • @miragebeyehu8460
    @miragebeyehu8460 2 роки тому

    idk anything about reincarnation but if it exists you're going to be the happiest, most fortunate person in your next life
    TYSM

  • @tmk5472
    @tmk5472 4 роки тому +14

    you sound like lil tecca if he was a teacher but good vid.

  • @Rgrin1133
    @Rgrin1133 2 роки тому

    I'm genuinely curious what is the actual difference between a teacher doing this in class and me watching this video. Is it the intent? Is it because I searched this up purposely? Is because I get easily distracted in a classroom? I don't know why it's so easy to understand these videos and so hard when it's in class or in a book!? Does anyone have any idea why?

  • @neebinelliott7523
    @neebinelliott7523 5 років тому +3

    This is 1000x better than Virtual High school. Never do a course with their online program.

  • @salvinsyed2831
    @salvinsyed2831 Рік тому

    I don't understand how you figure out what quadrant theta is in

  • @byrone.932
    @byrone.932 4 роки тому

    Where did you get that 4 on 3:37

  • @123pEpicGuy
    @123pEpicGuy 6 років тому +1

    Helped so much.Thnx

  • @adamharoon6021
    @adamharoon6021 4 роки тому +1

    9:56 I thought the hypotenuse would also be negative since tangent is negative in this quadrant... ASTC

  • @naomiparsons462
    @naomiparsons462 11 місяців тому

    Why would you want sin(2x), or cos(2x) or tan(2x)? How can you use this information? I'm learning trig purely off UA-cam so I don't know these things.