Find the exact value of the expression sin 265 degree cos 25

Find the exact value of the expression. sin 265 degree cos 25 degree - cos 265 degree sin 25 degree squareroot 3/2 - squareroot 3/2 - 1/2 - 53/12

Solution

Sin 265 cos 25 - cos 265 sin 25

This is of the form

Sin A cos B - cos A sin B which is equal to sin(A-B)

Therefore sin 265 cos 25 - cos 265 sin 25= sin(265-25) = sin 240

=-sqrt3/2

Correct option is B