1+cos2x= 2cos2x;
using this and putting it in given expression I will get cosx = sin-1sinx. ,-π <= x <= π
Now draw the curves of cosx for -π <= x <= π and also draw the curve of sin-1sinx for -π <= x <= π and find the no. of intersection points of the curve. They will intersect at two points only.
So, Ans is 2.