Question

Express cos(27pi/8) as a trigonometric function of an angle in Quadrant I.

Answer 1

Answer:

c on edgen

Step-by-step explanation:

Answer 2

Answer:

The equivalent trigonometric ratio in Quadrant I is $-\cos (\frac{3\pi}{8})$

Step-by-step explanation:

The terminal side of $\frac{27\pi}{8}$ is in the 3rd quadrant.

The principal angle is $\frac{3\pi}{8}$

In other words, the terminal side of $\frac{27\pi}{8}$  makes an acute angle of $\frac{3\pi}{8}$ radian with the positive x-axis. Acute angles are in the first quadrant.

Since the cosine ratio is negative in the 3rd quadrant,

$\cos (\frac{27\pi}{8})=-\cos (\frac{3\pi}{8})$