Question

evaluate cos 30°cos 45°-sin 30°sin 45°​

Answer 1

Cos 30 cos 45 - sin 30 sin 45
= root 3 / 2 * 1 / root 2 - 1 / 2 * 1 / root 2
= root 3 / 2 root 2 - 1 / 2 root 2
root 3 - 1 / 2 root 2

Hope that helps.