(a) Using the basis (sin(nt), sin(2nt), sin(4nt) }, defined for t from 1 to +1, find the best mean-square approximation of the function shown in Figure 2. Is this basis orthogonal ? (b) Find the best mean-square approximation of the function in Figure 2 using the function sin(2nt) (i.e. a basis with a single function). Compare the errors of the two approximations. Figure 2 65