Math homework due in 3 hours

Let V be a linear space with norm ?·?, W a subspace of V, and f ? V. Prove that the set of best approximations to f by elements in W is convex.Find the best uniform approximation to f(x) = sin2x on [0,2?] by polynomials of degree at most 2.Let f ? C[a, b]. Find the best uniform approximation to f by a constant.Let V = R3 with ?·?? and W = span{(0,1,0),(0,0,1)}. Let f = (3,6,4). Prove thata best approximation to f is not unique.Prove that every p ? Pn has a unique representation of the formp(x)=a0 +a1T1(x)+…+anTn(x), (1) where Tj , for j = 1, . . . , n are the Chebyshev polynomials of degree j.Plot T1, T2, T3 and T6.