To rotate a 2D Vector by 90 degrees about the origin, you would use...?

To rotate a 2D Vector by 90 degrees about the origin, you would use...?

The product of a 2x2 matrix and a column vector.

[ 0 -1 ] [x] = [-y]
[ 1 0 ] [y] [ x]

Note: you can get the same result by using the transpose of the matrix and multiplying on the left ("premultiplying") with a row vector.