Python source code: plot_exercice_4.py

import numpy as np

pl.figure(figsize=(8, 5), dpi=80)
pl.subplot(111)

X = np.linspace(-np.pi, np.pi, 256, endpoint=True)
S = np.sin(X)
C = np.cos(X)

pl.plot(X, C, color="blue", linewidth=2.5, linestyle="-")
pl.plot(X, S, color="red", linewidth=2.5, linestyle="-")

pl.xlim(X.min() * 1.1, X.max() * 1.1)
pl.ylim(C.min() * 1.1, C.max() * 1.1)

pl.show()