Question

find the exact value of 2 cos^2 (pi/8) -1

Answer 1

Trig identities can get this simpler. Did my last response show up? I've got bad connection at the moment.

Answer 2

didn't show up . im still pretty confused

Answer 3

\[\cos ^{2} (x)+\sin^{2}(x)=1\] Double both sides: \[2\cos ^{2} (x)+2\sin^{2}(x)=2\]
Subtract 1 from each side:
\[2\cos ^{2} (x)+2\sin^{2}(x)-1=1\]
Now do you see your equation?