expressions a If cos2 30 sin2 30 cos Ao then degrees b If

expressions. (a) If cos2 30° _ sin2 30° = cos Ao, then degrees (b) If cos2 82.-sin2 8x = cos B, then

Solution

a. cos²30 -sin²30 which is of the form cos²A-sin²A , that is equal to cos(2A)

SO we get cos(2*30)=cos 60

Hence A=60 degree

b. cos²8x -sin²8x which is of the form cos²A -sin²A , that is equal to cos (2A)

So we get cos(2*8x)=cos (16x)

Hence B=16x