python 圆曲线

import numpy as np
import matplotlib.pyplot as plt
a = 2
t = np.linspace(0 , 2 * np.pi, 1024)
X = a*np.cos(t)
Y = a*np.sin(t)
plt.title('$x=ρcosθ,y=ρsinθ$')
plt.plot(Y, X,color='r')
plt.show()