Sin grpah

import scipy.optimize as opt
import numpy as np
import matplotlib.pyplot as plt


Fs = 8000
f = 3
sample = 8000
x = np.arange(sample)
y = np.sin(2 * np.pi * f * x / Fs)
y1 = 0.5*np.sin((2 * np.pi * f * x / Fs)+(np.pi/2))
y2 = 0*x + 0

plt.plot(x, y)
plt.plot(x, y1)
plt.plot(x, y2, '#000000')
plt.xlabel('sample(n)')
plt.ylabel('voltage(V)')

ax=plt.subplot()
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.axes.xaxis.set_visible(False)
ax.axes.yaxis.set_visible(False)

#plt.title('test')
plt.xlabel('Test', labelpad=10)
plt.ylabel('Test', labelpad=10)
#plt.text(1, -7,'matplotlib', horizontalalignment='left',verticalalignment='center')

plt.show()