text: express 2sin^2θ + 3cosθ as a quadratic function of cosθ? can someone help me solve this:  express 2sin^2θ + 3cosθ as a quadratic function of cosθ  many thanks the expression is: 2*sin^2(θ) + 3*cos(θ) = 2*{1-cos^2(θ)} + 3*cos(θ) = 2 + 3*cos(θ) - 2*cos^2(θ) = {2 + 4*cos(θ)} - {cos(θ) + 2*cos^2(θ)} = 2{1 + 2*cos(θ)} - {cos(θ)}{1 + 2*cos(θ)} = {1 + 2*cos(θ)}{2 - cos(θ)}