# Python program to calculate arc length of an angle

In this session, we are going to learn how to calculate the arc length of an angle in Python.

## Find out the arc length of an angle in python

Arc length:

Arc length is defined as the certain length of a circumference of a given circle.

The formula for the arc length:

```Arc_length = (math.pi*d) * (A/360)
where d= diameter of the circle.
A=angle enterd by the user.```

let’s see coding part of the arc length.

1st import the math package for using PI’s value.

```#import math package to use math.pi for the value of PI
import math
```

create a function which takes the value from the user and perform all operations:

```#create a function to calculate the arc length.
def Arclength():
# take input diameter and angle .
d= float(input("please Enter the diameter of circle: "))
Angle = float(input("please Enter the angle value: "))
# checking for the angle validation
if Angle >= 360:
print("Invalid angle entered ")
return
#calculate  arc length.
Arc_length = (math.pi*d) * (Angle/360)
```

call the function and retrieve all the results.

```    print("the arc Length will be : %.2f" %Arc_length)
#function call
Arclength()
```

Now combine the whole program:

```#python code for finding the arc length of the angle.

##impotr math package to use math.pi for the value of PI
import math
#create a function to calculate the arc length.
def arclength():
# take input diameter and angle .
d= float(input("please Enter the diameter of circle: "))
Angle = float(input("please Enter the angle value: "))
# checking for the angle validation
if Angle >= 360:
print("Invalid angle entered ")
return
#calculate  arc length.
Arc_length = (math.pi*d) * (Angle/360)
print("the arc Length will be : %.2f" %Arc_length)
#function call
arclength()
```

Output:

```please Enter the diameter of circle: 9
please Enter the angle value: 45
the arc Length will be : 3.53```

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