Posted by **Jillian** on Tuesday, January 20, 2009 at 3:57pm.

Prove the identity.

sinē θ = tanē θ / 1 + tanē θ

- Math -
**drwls**, Tuesday, January 20, 2009 at 4:37pm
I assume the right side is supposed to be tanē č /(1 + tanē č)

Start by rewriting

1 + tan^2 = (cos^2 + sin^2)/cos^2

= 1 /cos^2

so that

1/(1+tan^2) = cos^2

Therefore the right side becomes

(sin^2/cos^2)* cos^2 = sin^2

- Math -
**Jillian**, Tuesday, January 20, 2009 at 4:46pm
how did 1 + tan^2 become cos^2 + sin ^2?

- Math -
**Jillian**, Tuesday, January 20, 2009 at 4:54pm
oh nevermind i got it thank you.

- Math -
**Jillian**, Wednesday, January 21, 2009 at 5:45pm
Cool

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