Question

PLEASE ANSWER ASAP

Use complete sentences to explain the relationship between cos 7pi/6 and cos 5pi/6. In your answer, reference specific values on the unit circle to prove the relationship between the angles.

Answer 1

The relationship is that cos 7pi/6 and cos 5pi/6 both are cosines of angles that have a reference angle of pi/6. cos 7pi/6 = cos 5pi/6 = -√3/2

Answer 2

It is known

`(\pi)/(6) =30^(\circ)` and

`\cos (\pi)/(6)= ( √(3) )/(2)` (if you want to determine cosine of 30° you should draw the perpendicular line to the x-axis and find the point of intersection, the value of x-coordinate is the cosine of 30°).

The angle
`(5\pi)/(6) =150^(\circ)` and

`\cos (5\pi)/(6)=- ( √(3) )/(2)` (see image).
The angle
`(7\pi)/(6) =210^(\circ)` and


`\cos (7\pi)/(6)=- ( √(3) )/(2)` (see image).