hi i am stuck in Questions 3 and 4 can someone help me,

R= 1, Sink, Cos x, Sin 2x, cos ax $ Sin 3x, (05 3x 3 . REC 1. Show this set is orthogone with (figs: " frogends 2. Find an orthonormal basis for span ( B ). Given a cont function fex over [-m, NT ] 6.6 3. # 3) find proj fox Sp ( B ) Fourier 4 . led fox ) = x over [-IT/ T'] find proj frog Span $89 5 . Compare your results w/ Fourier series for a periodic function