Half-Angle Formula for Exact Values

Question

Use the half-angle formula to find the exact values

cos67°30'=

Can you please show me how to do this?

Answer 1

67° 30' = (0.5)(135°)

As stated in the problem use the Half-Angle Formula±

cos (135 / 2)° = ±√[(1 + cos 135°) / 2]