Find all solutions in the interval 0 360 degree COS 2x Squa

Find all solutions in the interval [0, 360 degree]. COS (2x) = -Squareroot 3/2 15 degree, 30 degree, 105 degree, 120 degree, 195 degree, 210 degree, 285 degree, 300 degree 0 degree 75 degree, 105 degree, 255 degree, 285 degree 45 degree, 225 degree

Solution

0^o<=x<=360^o

=>0^o<=2x<=720^o

cos(2x)=-3_/2

=>2x =150^o,210^o,510^o,570^o,

=>x =75^o,105^o,255^o,285^o,