if Ø is an angle in the first quadrant and cosØ= 1/2, find the exact value of cos2Ø

Answer 1

This is almost the same kind of question that I answered for you here :
http://www.jiskha.com/display.cgi?id=1456693077

Did you look at it, and learn from it?
I will give you one hint for this one:
cos (2Ø) = cos^2 Ø - sin^2 Ø

let me know how you made out.

Answer 2

oh ok i think i understand how to do them know...thank you

Answer 3

Tell me what you got, then we'll both be happy