Hint 8.14

(1) You may find the following trig identities helpful:

• sin(θ)=cos(90°–θ)
• sin²θ = 1–cos²θ

(2) You will need to solve an equation something like Ax⁴ + Bx² + C = 0. Note that if you make the substitution z = x², the equation is just Az² + Bx + C = 0, a standard quadratic equation.