Question

The matrix of the transformation reflection in the line x + y = 0 is

(A) [(1, 0), (0, 1)]

(B) [(0, 1), (1, 0)]

(C) [(-1, 0), (0, -1)]

(D) [(0, -1), (-1, 0)]

Answer 1

Answer is (D) [(0, -1), (-1, 0)]

After reflection in line x + y = 0, y becomes x. Therefore, we need a matrix which when multiplied by

We observe that

Hence, matrix of transformation is [(0, -1), (-1, 0)]