Express as a trigonometric function of one angle. cos 16° cos 48° − sin 16° sin 48°

Question

Express as a trigonometric function of one angle.

cos 16° cos 48° − sin 16° sin 48°

Answer 1

cos(16)cos(48) - sin(16)sin(48)

To solve this, we use the angle sum formula for cos: cos(a + b) = cos(a)cos(b) - sin(a)sin(b).

So cos(16)cos(48) - sin(16)sin(48) = cos(16 + 48) = cos(64)