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...

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- Nov 20th 2010, 09:07 AMmike789Evaluate 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... - Nov 20th 2010, 09:15 AMharish21
$\displaystyle \cos(180-x)=-\cos(x)$

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