Deriving Trigonometric Identies from Known Identities

[MEGAxxxDETH666]

I;m really good at those.

[ugcxft23]

I love you is a understatement *_*

[TaylorTV5]

Thanks man. You just taught me in about 20 minutes (I watched the other identities video) what my teacher had failed to teach me in 5 days. You deserve a Nobel Peace Prize.

[Edey02]

great job! :)

[sergefabregas]

patrick is sumthing that switches my brain on haha

[SirStrum]

You are amazingly clear! Thank you!

[dovegirl17]

What I meant to say Trig Identities :) :P

[dovegirl17]

Thank you Now I finally understand trig :)

[supermadcrazy]

theres much more simple way in figuring out which trigonometric functions er even or odd.........the functions starting with "CO" er even...like cosine,cosec,cotangent....nd others er odd......like sine,tangent.sec.....

[applekiwibanana]

THANK YOU SO MUCH. I've been looking everywhere for something like this. I wish I had you as a teacher. =(

[iTzJimBoi]

For the first few trig identities, if you took the square root of both sides would the equality still stand? Like sin(x)+cos(x)=1 and 1+cot(x)=csc(x)?

[paddy2k6]

@iTzJimBoi

It wont equal 1 tho it wil be root 1, so it would only complicate things.

well thats how i see it :)

[CubemalaUnited]

@iTzJimBoi The answer from paddy2k6 is wrong. If you take the square root of both sides you would get the square root of a sum = the square root of the answer:

(sinx^2+cosx^2)^1/2=(1)^1/2=1. You cannot square root the factors of a sum seperately so it just makes more work for you. Same with 1+cotx^2=cscx^2.

[VangY34311]

SSSSSSSSSSSSSSSSSSSSSSSSomethi­ng lol

[anthonychemistry]

Thank you. You are so helpful. How about Half angle? do u have a simple way to derive that? please help..

[mekanopsis1]

Don't know if it was this one where you mentioned a mnemonic - sin is something that switches.....

I made up one I prefer.

sin is something that combines

(cos and sin on each side of the operator)

cos is something that switches

(sign of the operator)

[kyoyaoliver10th]

how do you solve sinx + siny ?

[cliffsasexybeast]

use the formula sinx * cosy + cosx * siny

[stoopidkevin]

omg, now I dont have to remember all those identities!

YOUTUBE > TEACHERS

[kpbotbot]

he didn't include the other deriving stuff found at 8:00 to the first stuff :D still, awesome video.

[PistolPete771]

wow...i thought this was impossible until now

[kdelmonten]

just donated... Everyone... donate through secure PayPal so we can continue to enjoy these free vids...

[nosajbaconandegs]

Man I tried to make up some way to remember these for a while but none of them were as useful as yours. Thanks!!!!

[kataridragon]

Wow I just had an aneurysm trying to figure this out. Yet it was so easy. Thanx "5 Stars"

[ricky0633milano]

are there any good ways to memorise tangent identities...?

[trickykate]

this is SO helpful - thank you so much!

[dewi20]

ausum

[t0myuri]

I'm confused. When I factorise a quadratic with trig inside it, I get the numbers out, but then what do I do?

[kidpr0zac]

your videos are really helpful! thank you! =]

[mawnickugh]

thanks, this helped a ton!

but is there any way to derive the half-angle identities from these 3?

[ricky0633milano]

they are the same with double angle...except you have to divide the theta by 2...

[ptboy18]

gracias por su ayuda=] oh how does that pick up line go? You be sin^2 and I'll be cos^2 and together be as 1.....my calc teacher used it on me, i thought it was cute

[patrickJMT]

lol, nothing like a teacher hitting on a student

[t0myuri]

hehe

[theredmars]

@ptboy18 is your teacher Mary Kay Letourneau?

[theredmars]

@ptboy18 is your teacher Mary Kay Letourneau?

[patrickJMT]

use the first identity to prove or disprove it!

[tzone92]

if sin(2x)=2sinx cosx, is sin(3x)=3sinx cosx?

[bagelace]

damm thanx alot for the review...it help me remember the indentities....thanx

[danepi99]

gracias por su ayuda,,,me sirvio mucho este video,,,

[tHAnamEsLiLixD]

AMAZING! thanks so much for your help. i have a math test soon.

THANK YOU!!! :D

[DKfansown]

wow, thanks a lot dude. this really helps me out. p.s. hola from the city south of austin.

[patrickJMT]

nice! you from san antonio? i moved here a year ago, and still not 100% on all the towns around here : )

saw you liked the dead kennedys! nice! i saw jello give one of his 'rants' back in nashville when i lived there. he acted and sounded just like he did from back in the day!

[botski222222]

thank you...

[patrickJMT]

no problem! learn 3, get the rest! much better than tons of memorizing!