Question 1010316
2sin^2x-1=0 
2(1-cos^2x)-1=0
2- 2cos^2x-1=0
-2cos^2x+1=0
1=2cos^2x
2cos^2x=1
cos^2x=1/2
cosx=±√(1/2)=±√2/2
x=45, 135, 225 and 315 deg (from 0 to 2pi)