a) Find constants a, b, c, d, and e such that
cos(4theta) = a(sin(theta))^4 + b(sin(theta))^3 + c(sin(theta))^2+ d sin(theta)+ e for all angles theta. In other words, write cos(4theta) as a polynomial in sin theta.
b) Prove that
sin (18 degrees)= cos (4 * 18 degrees) using right triangles or the unit circle.
c) Use a) and b) to solve for sin(18 degrees)
