# Python cos

The Python cos function is one of the Math functions which calculates the Trigonometry Cosine for the specified expression. The Python cos function returns the value between -1 and 1, and in this section, we discuss how to use this math function with an example.

The mathematical formula behind the Trigonometry Cosine function is

COS(x) = Length of the Adjacent Side / Length of the Hypotenuse

The syntax of the cos Function in Python Programming Language is

`math.cos(number);`

Number: It can be a number or a valid numerical expression for which you want to find the Cosine value.

• If the number argument is a positive or negative number, the cos function returns the Cosine value.
• If it is not a number, this function returns TypeError.

## Python cos Function Example

The Python cos Function allows finding the trigonometry Cosine for the numeric values. In this example, we are going to find the Cosine values of different data types and display the output.

TIP: Please refer acos method article to find the Arc Cosine of the specified Python expression.

First, We declared List and Tuple with some random values. Next, we used this Python cos method directly on both positive and negative integers. The first two statements find the Cosine of the corresponding values.

Next, We used the cosine Function on Tuple and List items. The above screenshot shows that the function is working perfectly on them.

Next, We used this math method on multiple values. Within the last statement, we tried on the String value, and it returns TypeError.

```import math

Tup = (1, 2, 3, -4 , 5)
Lis = [-1, 2, -3.5, -4 , 5]

print('Cosine value of Positive Number = %.2f' %math.cos(10))
print('Cosine value of Negative Number = %.2f' %math.cos(-15))

print('Cosine value of Tuple Item = %.2f' %math.cos(Tup[3]))
print('Cosine value of List Item = %.2f' %math.cos(Lis[2]))

print('Cosine value of Multiple Number = %.2f' %math.cos(10 + 20 - 40))
print('Cosine value of String Number = ', math.cos('Hello'))```