Find the standard matrix of the linear transformation T: R² -> R² rotates points (about the origin) through 3/4 pi radians (with counterclockwise rotation for a positive angle).
a) [cos(3/4π), -sin(3/4π); sin(3/4π), cos(3/4π)]
b) [cos(π/4), -sin(π/4); sin(π/4), cos(π/4)]
c) [cos(π/2), -sin(π/2); sin(π/2), cos(π/2)]
d) [cos(π), -sin(π); sin(π), cos(π)]
