Let B = {1; cos t; cos 2t; cos 3t; cos 4t} and C = {1; cos t; cos²t; cos³t; cos⁴t}.

1. Use trigonometric identities to write each element of B as a linear combina-

tion of the elements of C. [Hint: You really only need the (rst) Pythagorean

identity and the angle addition formulas.]