Question

Express cos 170 as a function of the reference angle.Question 10 options:-cos10cos190-cos190cos-10

Answer 1

Given: cos 170

We will express (cos 170) as a function of the reference angle.

The given angle (170) falls in the second quadrant

The reference angle for the angles in the second quadrant = 180 - θ

So,

$\cos 170=\cos (180-10)=-\cos 10$

So, the answer will be: -cos 10