The `cos()` function will return the cosine of a number. To be more specific, it returns the cosine of a number in *radians*. 

Figure 1 shows the mathematical representation of the `cos()` function.

>Note:
>- The `math` module is required for this function.
>- This `cos()` function only works for right-angled triangles. 



# Syntax
```python
cos(num)
```
# Parameter
This function requires a `number` that represents an `angle` in `radians` as a parameter.

To convert `degrees` to `radians`, use the following formula:
```python
radians = degrees * ( pi / 180.0 )
```

# Return value
`cos()` returns the `cosine` of a number `(radians)` that is sent as a parameter. The return value is in the range `[-1,1]`.

# Example


import math

#positive number in radians
print "The value of cos(2.3) : ",  math.cos(2.3)

#negative number in radians
print "The value of cos(-2.3) : ",  math.cos(-2.3)

#converting the degrees angle into radians and then applying cos()
#degrees = 180
#PI = 3.14159265
result = 180.0 * (math.pi / 180.0)
print "The value of cos("+str(result)+") : ",  math.cos(result)

What is math.cos() in Python?

Returns the cosine of a number in radians, requiring the math module and radians as input.