Find the Value Using the Unit Circle (5pi)/3

Evaluate .
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
The exact value of is .
Evaluate .
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because sine is negative in the fourth quadrant.
The exact value of is .
Set up the coordinates .
Find the Value Using the Unit Circle (5pi)/3