(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Prove that the Given Equation is an Identity:

Code (Text):sin2A

------ = cotA

1 - cos2A

2. Relevant equations

sin(A+B) = sinAcosB + cosAsinB

cos(A+B) = cosAcosB - sinAsinB

tan(A+B) = (tanA + tanB) / (1 - tanAtanB)

sin2A = 2sinAcosA

cos2A = cos[tex]^{}2[/tex]A - sin[tex]^{}2[/tex]A

tan2A = 2tanA / 1 - tan[tex]^{}2[/tex]A

3. The attempt at a solution

I tried changing sin2A to sin(A+A) and arrived at 2sinAcosA at the top.

I also tried changing 1 - cos2A to 1 - cos[tex]^{}2[/tex]A - sin[tex]^{}2[/tex]A, but then I arrived at having a 0 in the denominator.

I'm really not sure where to start in trying to prove the identity. I understand that I should not touch the cotA on the right hand side, but no matter what I do to rewrite the left side I can't seem to arrive at the cotA.

I would appreciate it if someone could point me in the right direction. Thank you in advance for the assistance.

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# Homework Help: Prove that the Given Equation is an (Trig) Identity

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