Converting Between Polar and Rectangular Form
Given points or equations
17.30 In the diagram below, point P has rectangular coordinates (x,y) and polar coordinates (r,θ). Apply trigonometric ratios to express x and y in terms of r and θ.
Note that the diagram contains a right triangle, so you can apply trigonometric ratios to describe the relationship between r, θ, x, and y.
Cross-multiply to solve the equations for x and y, respectively.