# Python | math.cos() function

Last Updated : 20 Mar, 2019

In Python, math module contains a number of mathematical operations, which can be performed with ease using the module. math.cos() function returns the cosine of value passed as argument. The value passed in this function should be in radians.

Syntax: math.cos(x)

Parameter:
x : value to be passed to cos()

Returns: Returns the cosine of value passed as argument

Code #1:

 # Python code to demonstrate the working of cos()        # importing "math" for mathematical operations   import math        a = math.pi / 6       # returning the value of cosine of pi / 6   print ("The value of cosine of pi / 6 is : ", end ="")   print (math.cos(a))

Output:

The value of cosine of pi/6 is : 0.8660254037844387


Code #2:

 # Python program showing   # Graphical representation of   # cos() function   import math  import numpy as np  import matplotlib.pyplot as plt      in_array = np.linspace(-(2 * np.pi), 2 * np.pi, 20)     out_array = []     for i in range(len(in_array)):      out_array.append(math.cos(in_array[i]))      i += 1        print("in_array : ", in_array)   print("\nout_array : ", out_array)      # red for numpy.sin()   plt.plot(in_array, out_array, color = 'red', marker = "o")   plt.title("math.cos()")   plt.xlabel("X")   plt.ylabel("Y")   plt.show()

Output:

in_array : [-6.28318531 -5.62179738 -4.96040945 -4.29902153 -3.6376336 -2.97624567
-2.31485774 -1.65346982 -0.99208189 -0.33069396 0.33069396 0.99208189
1.65346982 2.31485774 2.97624567 3.6376336 4.29902153 4.96040945
5.62179738 6.28318531]

out_array : [1.0, 0.7891405093963934, 0.2454854871407988, -0.40169542465296987, -0.8794737512064891, -0.9863613034027223, -0.6772815716257412, -0.08257934547233249, 0.5469481581224268, 0.9458172417006346, 0.9458172417006346, 0.5469481581224268, -0.0825793454723316, -0.6772815716257405, -0.9863613034027223, -0.8794737512064893, -0.40169542465296987, 0.2454854871407988, 0.7891405093963934, 1.0]

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