D dagr8est Junior Member Joined Nov 2, 2004 Messages 128 Dec 6, 2005 #1 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.
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 Elite Member Joined Jan 29, 2005 Messages 11,978 Dec 6, 2005 #2 \(\displaystyle \L \cos (2x) = \cos ^2 (x) - \sin ^2 (x)\) \(\displaystyle \L 3\sin ^2 (x) - 3\cos ^2 (x) = - 3\left( {\cos ^2 (x) - \sin ^2 (x)} \right)\)
\(\displaystyle \L \cos (2x) = \cos ^2 (x) - \sin ^2 (x)\) \(\displaystyle \L 3\sin ^2 (x) - 3\cos ^2 (x) = - 3\left( {\cos ^2 (x) - \sin ^2 (x)} \right)\)
D dagr8est Junior Member Joined Nov 2, 2004 Messages 128 Dec 6, 2005 #3 Oh shiz, I did not think about using a double angle backwards like that.
