Question

When Θ = 5 pi over 6, what are the reference angle and the sign values for sine, cosine, and tangent?

Answer 1

Note that (5π)/6 radians = 150°. Therefore the given angle is in quadrant 2.

Refer to the figure shown below.

Reference angles are measured relative to the horizontal axis.
Therefore the reference angle in each quadrant is π/6 radians or 30°.
Denote the reference angle as θ'.
Then, in quadrant 1,
cos θ' = √3/2,  sin θ' = 1/2,  tan θ' = √3.

Because we are in quadrant 2,
  sin θ' = π/6;
  sin(5π/6) is positive, but cos (5π/6) and tan (5π/6) are negative.

 Answer:
5π/6 is in quadrant 2.
The reference angle, θ' = π/6.
sin(5π/6) is positive, cosine and tangent are negative.

Answer 2

Answer:

5π/6 is in quadrant 2.

The reference angle, θ' = π/6.

sin(5π/6) is positive, cosine & tangent are both negative