import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 2*np.pi, 30)
y1 = np.cos(x)
y2 = np.sin(x)

plt.plot(x, y1, label="cos(x)")
plt.plot(x, y2, label="sin(x)", linewidth=4)
plt.legend()

plt.show()