a. Given that 2 cos = 1 + 3 sin , show that R cos ( + ) = 1, where R and

a. Given that 2 cos θ = 1 + 3 sin θ, show that R cos (θ + α) = 1, where R and α are constants to be found.

b. Hence, or otherwise, solve 2 cos θ = 1 + 3 sin θ for 0 ≤ θ ≤ 360°.