# Evaluate 1-2(cos^2)25/1-2(sin^2)65

• November 20th 2010, 09:07 AM
mike789
Evaluate 1-2(cos^2)25/1-2(sin^2)65
Help me out with this evaluate question plz..

Evaluate:

1-2(cos^2)25/1-2(sin^2)65
Give the answer in surd form

I did some steps but don’t know if it’s wrong or right
-cos2(25)/cos2(65)
-cos50/cos130
Don’t know how to take it any further...
• November 20th 2010, 09:15 AM
harish21
$\cos(180-x)=-\cos(x)$

$-\cos(50)=-[\cos(180-130)]=...$