[Jtehanonymous]

Hey everyone. I was wondering if I could have some help with two questions I'm currently stuck on. I was a little unsure whether I should post in this forum since it's basically dead...but I was hoping someone would find their way in here and help out. xD

1) Let A be a 7x5 matrix of rank 4. Let P and Q be the projection matrices which project vectors in R^7 onto R(A) and N(A^T). Find the inverse of P-Q.


2) What is the closest function, a cos(x) + b sin(x), to the function f(x) = sin(2x) on the interval from 0 to pi?


Any help or ideas at all would be greatly appreciated. Thanks!