#範例11-5：求點(-2,1,2)，以y軸為中心旋轉45°旋轉後的像。
import numpy as np
rad = np.radians(45)
T1 = np.array([
    [np.cos(rad),0,np.sin(rad)],
    [0,1,0],
    [-np.sin(rad), 0, np.cos(rad)]
    ])
x = np.array([
    [-2],[1],[2]
    ])
y = T1 @ x
print('以y軸為中心旋轉45°旋轉後的像=\n', y)