# How to Find Cosine in Python

To compute the cosine of an angle using Python, you can utilize the **cos()** function from the `math` library.

import math

math.cos (x)

Here, "x" represents the angle in radians.

The **cos(x)** function returns the cosine value of "x".

**Understanding the Cosine Function**.** **In trigonometry, the cosine represents the ratio between the side adjacent to the angle (OA) and the hypotenuse (OB). The cosine value is 1 when the angle is 0 degrees and 0 when the angle is 90 degrees.

## Example

__Example 1__

This script calculates the cosine of a 45° angle.

The **math.radians()** function is used to convert degrees into radians.

import math

x = math.radians (45)

math.cos (x)

The output for the above code is:

0.7071067811865476

Thus, the cosine of a 45° angle (π/4 radians) is approximately 0.7071067811865476.

__Example 2__

This script calculates the cosine of a 45° angle using π (π ≈ 3.14) to represent radians.

import math

x = math.pi / 4

math.cos (x)

In the "math" library, π is represented as **math.pi**.

The output for this code is also:

0.7071067811865476

This is the same result as in the previous example, but derived in a different manner.

**Note**. The cosine function in Python doesn't return an exact zero value for angles of 90° and 270°. Instead, it returns a very small value close to zero. This can be problematic in certain applications. To mitigate this, it's recommended to round the result of `cos(x)` to at least 5 decimal places. In Python, the cosine values for 90° and 270° are not precisely zero.

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