Posted by **Yadira** on Monday, May 14, 2012 at 7:15pm.

Prove Identity: (1-cos2x/ tan x) = sin2x

- Pre-Calc/Math -
**MathMate**, Tuesday, May 15, 2012 at 5:18am
I think the parentheses are in the wrong place. It should probably read:

(1-cos2x)/tan x = sin2x

Again, split everything into sin and cos, and don't forget the identities:

cos(2x)=cos²(x)-sin²(x)

sin(2x)=2sin(x)cos(x)

(1-cos(2x))/tan(x)

=(1-(cos²(x)-sin²(x))*(cos(x)/sin(x))

=(1-(1-2sin²(x))*cos(x)/sin(x)

=2sin²(x)*cos(x)/sin(x)

=2sin(x)cos(x)

=sin(2x)

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