Can someone help me prove two theorems? I know they both are true, but can't come up with proofs. 1) Prove that a 3x3 matrix A is orientation preserving iff det(A)>0. 2) Prove that for A, B (both 3x3 matrices) that det(AB)=detA*detB. (A, B may or may not be invertible). THANK YOU!!!!