SOLUTION: 2sin^2 x+15cosx-9=0

Algebra ->  Test -> SOLUTION: 2sin^2 x+15cosx-9=0      Log On


   

Question 1154342: 2sin^2 x+15cosx-9=0
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
2sin^2 x+15cosx-9=0

2(1-cos^2x) +15 cosx -9=0
2-2cos^2x +15cosx -9=0
2cos^2x -15cosx +7=0
2cos^2x -14cosx-cosx +7=0
2cosx(cosx-7)-1(cosx-7)=0
(cosx-7)(2cosx-1)=0
cosx =7 , or cos x =1/2