Question

Question #9c136

Answer 1

`Cos80- Sin10 = 0`

Explanation:

In trigonometry, if 2 angles are complementary (ie. add up to 90°), then the Cos of one = Sin of the other.

If `theta + beta = 90° " then "Sin theta = Cos beta`,

(Hence their names Sine and Cosine)

`Cos 80 = Sin 10`

`:. Cos80- Sin10 = 0`