# math.acos() method with example in Python

Python math.acos() method: Here, we are going to learn about the math.acos() method with example in Python.
Submitted by IncludeHelp, on April 21, 2019

## Python math.acos() method

math.acos() method is a library method of math module, it is used to get the arc cosine, it accepts a number between -1 to 1 and returns the arc cosine value (in radians) of the given number.

Note: math.acos() method accepts the only number between the range of -1 to 1, if we provide number out of the range, it returns a ValueError - "ValueError: math domain error", and if we provide anything else except the number, it returns error TypeError - "TypeError: a float is required".

Syntax of math.acos() method:

```    math.acos(x)
```

Parameter(s): x – is the number whose arc cosine to be calculated.

Return value: float – it returns a float value that is the arc cosine value of the number x.

Example:

```    Input:
a = 0.278

# function call
print(math.acos(a))

Output:
0.2853901924877167
```

### Python code to demonstrate example of math.acos() method

```# python code to demonstrate example of
# math.acos() method

# importing math module
import math

# number
a = -1
print("acos(",a,") is = ", math.acos(a))

a = 0
print("acos(",a,") is = ", math.acos(a))

a = 0.278
print("acos(",a,") is = ", math.acos(a))

a = 1
print("acos(",a,") is = ", math.acos(a))
```

Output

```acos( -1 ) is =  3.141592653589793
acos( 0 ) is =  1.5707963267948966
acos( 0.278 ) is =  1.2890849198520296
acos( 1 ) is =  0.0
```

ValueError example

```# python code to demonstrate example of
# math.acos() method with an exception

# importing math module
import math

# number
a = 2
print("acos(",a,") is = ", math.acos(a))
```

Output

```Traceback (most recent call last):
File "/home/main.py", line 9, in <module>
print("acos(",a,") is = ", math.acos(a))
ValueError: math domain error
```

TypeError example

```# python code to demonstrate example of
# math.acos() method with an exception

# importing math module
import math

# number
a = "2"
print("acos(",a,") is = ", math.acos(a))
```

Output

```Traceback (most recent call last):
File "/home/main.py", line 9, in <module>
print("acos(",a,") is = ", math.acos(a))
TypeError: a float is required
```

Preparation