Trig - Simplifying Expressions

[dagr8est]

Simplify using sum and difference or double angle identities.

3sin^2(pi/8)-3cos^2(pi/8)

I cannot figure out how to express pi/8 using two special angles. Believe me; I tried for a long long long long... you get the idea.

 

[pka]

\(\displaystyle \L
\cos (2x) = \cos ^2 (x) - \sin ^2 (x)\)

\(\displaystyle \L
3\sin ^2 (x) - 3\cos ^2 (x) = - 3\left( {\cos ^2 (x) - \sin ^2 (x)} \right)\)

 

[dagr8est]

Oh shiz, I did not think about using a double angle backwards like that.