{(-2, 6), (-5, -1), (3, 7), (-5, 0)}
Domain: The domain is all the x-values (-2, -5, 3, -5)
Range: The range is all the y-values (6, -1, 7, 0)
Function: It's not a function because of the x-value -5 is repeating.
Using the cosine double angle formula,
(Note I took the positive case since terminates in the first quadrant)
Using the Pythagorean identity,