- #1

TbbZz

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## Homework Statement

Prove that the Given Equation is an Identity:

Code:

```
sin2A
------ = cotA
1 - cos2A
```

## Homework 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

## 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.