Friday

July 25, 2014

July 25, 2014

Posted by **Simon** on Sunday, November 8, 2009 at 11:16pm.

I can't find any identities that can help me with this. I'm really confused

- Math -
**drwls**, Monday, November 9, 2009 at 10:22am1 + tan^2 x= (cos^2 x+ sin^2 x)/cos^2 x = 1/cos^2 x

Therefore

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

= cos 2x

**Related Questions**

Trig Identities - Proving identities: 1) 1+ 1/tan^2x = 1/sin^2x 2) 2sin^2 x-1 = ...

Math-Trigonometry - Show that if A, B, and C are the angles of an acute triangle...

Trigonometry desperate help, clueless girl here - 2. solve cos 2x-3sin x cos 2x...

Math - help really needed - Prove each idenity. 1+1/tan^2x=1/sin^2x 1/cosx-cosx=...

Math - help really needed - I'm sorry to double post; I don't want to seem ...

Trigonometry - Find the exact value of tan(a-b) sin a = 4/5, -3pi/2<a<-pi...

Trigonometry - 1.Solve tan^2x + tan x – 1 = 0 for the principal value(s) to two ...

trig - please help me. use trig. identities to find the exact value. tan 25° + ...

trig - please help me. use trig. identities to find the exact value. tan 25° + ...

Math - Prove Trig. Identities 1. sec è (sec è - cos è)= tan^2 è 2. tan^2 è (1 + ...