r_x-axis (x, y) -->

(x, -y)

r_{y -axis} (x, y) -->

(-x, y)

r_{y = x} (x, y) -->

(y,x)

r_{y = -x} (x, y) -->

(-y, -x)

r_origin (x, y) -->

or

r_O

(-x, -y) use with reflection

T_{a, b} (x, y) -->

(x +a, y +b)

_{O,90 (x, y)} -->

(-y, x)

R_{O,180 (x, y) -->}

(-x, -y)

R_{O,270 (x, y)} -->

(y, -x)