What is the value of cosθ given that (−2, 9) is a point on the terminal side of θ?
9√85/85
−9√85/85
2√85/85
−2√85/85
r = √ [ x^2 + y^2 ] = √ [ ( -2)^2 + 9^2 ] = √85
cos θ = -2 / √85 = -2√85 / 85
