Another problem:
Use matrix multiplication to find the projection of the vectors (3,4) (2,1) and (-3,2) during rotation for -30 deg. with center in the coordinate start (beginning).
tnx
The matrix in 1. rotates vectors -30 degrees, right. You don't need the matrix in 2. for anything.
The way the matrix rotates a vector is simply by multiplying the matrix with the vector, so to see where (-3,2) gets rotated, you multiply the matrix in 1. with the column vector
-3,
2,
in that order.