Question

Determine the sign of cos pi divided by seven without using a calculator.

Answer 1

The angle $\frac{\pi}{7}$ is in Quadrant 1 and cos of an angle in quadrant 1 is always positive

Answer 2

Answer:

The $\cos \frac{\pi}{7}$ has positive sign.

Step-by-step explanation:

we need to determine the sign of  $\cos \frac{\pi}{7}$ without using calculator

Cartesian system ( shown in figure -1)

The angle $\cos \frac{\pi}{7}$ lies in quadrant-1 , Where angles are zero (0) to $\frac{\pi}{2}$

and in first quadrant all trigonometric ratios has positive sign

so,  $\cos \frac{\pi}{7}$ has positive sign.