Calculate the standard matrix for each of the following linear transformations T.
a. T: R^2 -> R^2 given by rotating -pi/4 counterclockwise about the origin and then reflecting across the line x_1 - x_2 = 0.
b. T: R^3 -> R^3 given by rotating pi/2 counterclockwise about the x_1-axis (as viewed from the positive side) and then reflecting across the plane x_2 = 0.
c. T: R^3 -> R^3 given by rotating -pi/2 counterclockwise about the x_1-axis (as viewed from the positive side) and then rotating pi/2 about the x_3-axis.