Question

Which of the following equals cos 80°?

A) sin 100°
B) sin 10°
C) sin 20°
D) sin 80°

Answer 1

To find which option equals cos 80°, we use the co-function identity resulting in cos 80° being equal to sin 10°. Therefore, the answer is B) sin 10°.

Step-by-step explanation:

The question asks which of the following equals cos 80°: A) sin 100° B) sin 10° C) sin 20° D) sin 80°. To solve this, we can use the co-function identity that relates the sine and cosine functions: sin (90° - θ) = cos θ and cos (90° - θ) = sin θ. Applying this, we have cos 80° = sin (90° - 80°), meaning that cos 80° is equal to sin 10°. Therefore, the correct answer is B) sin 10°.