1. let f(x, y) be a differentiable function in the variables x and y. let r and θ the polar coordinates, and set g(r, θ) = f(r cos θ, r sin θ) in other words g is f in terms of polar coordinates. suppose that it is known that fx(1, 1) = −2 and fy(1, 1) = 3 use the chain rule in order to compute the partial derivative gr( √ 2, π/4).