Question

what is the value of (cos²67°-sin²23°)?

Answer 1

Cos²67° - sin²23°
= cos²67° - sin²(90 - 67)
= cos²67° - Cos²67°
= 0

Answer 2

Cos67^2-cos(90-23)^2
Cos67^2 -cos67^2
=0