Answer:
.
Reference angle is 
Step-by-step explanation:
Given the value of x. we have to find the correct value of cosx.

Now, we have to find the exact value of 



Now, we have to find the reference angle of
.
Since the angle
lies in second quadrant, the reference angle formula is
Reference angle=
.
=
Answer: i think its B
Step-by-step explanation: