Dimensions of a Matrix

Dimensions of a matrix are determined by looking at the rows and columns.

The columns are the numbers that go up or down (vertical) . The rows are the numbers that go across (horizontal) . The dimension, once again, is found by

Row X Column ( Horizontal X Vertical) .

This matrix has a dimension of 1 x 3 since it has ONE row and THREE columns.

This matrix has a dimension of 3 x 3 because it has THREE rows and THREE columns.

This is called the identity matrix, where 1's are in the diagonal line. This is called the identity matrix because if you multiply this matrix with another matrix, the answer will be the same as the other matrix.