[Knight Templar]

I have a trig test tomorrow and if I don't do well, well, I'll be ****ed to say the least. First person to walk me through each problem gets a cookie.

First problem: Find the exact value of each problem using Double-Angle or Half-Angle identities:  

Cos pi/8

[Knight Templar]

*Bizzump*

[Rictor]

where's CP gone off to anyway?

[Knight Templar]

He's probably off masturbating with a calculator. Damnit.

[Joey_21]

Half-angle identity:
cos²(½a) = ½(1+cos(a))
cos(½a) = Sqrt(½(1+cos(a)))
since we have cos(pi/8), let a = 2*pi/8 or pi/4

cos(½(pi/4)) = Sqrt(½(1+cos(pi/4)))
= Sqrt(½(1+Sqrt(2)/2))