Question
Really Stumped on this one, any help would be great! Thanks!
Find the exact value of cos 2x using the double angle formula.
cosx=−2/13 cosx=-2/13 where π2 <x < π
Find the exact value of cos 2x using the double angle formula.
cosx=−2/13 cosx=-2/13 where π2 <x < π
Answers
Steve
cosx = -2/13
cos2x = 2cos^2x - 1 = 2(4/169)-1 = -161/169
cos2x = 2cos^2x - 1 = 2(4/169)-1 = -161/169