# Python Program To find Area Of Circle

Write a python program to find area of circle using radius, circumstance and diameter. The Python area of a circle is number of square units inside the circle. Standard formula to calculate the area of a circle is: A=πr².

## Python Program to find Area Of Circle using Radius

If we know the radius then we can calculate the area of a circle using formula: A=πr² (Here A is the area of the circle and r is radius). In this python program, we will find area of a circle using radius.

```# Python Program to find Area Of Circle using Radius

PI = 3.14
circumference = 2 * PI * radius

print(" Area Of a Circle = %.2f" %area)
print(" Circumference Of a Circle = %.2f" %circumference)```

We defined pi as global variable and assigned value as 3.14. This python program allows user to enter the value of a radius. And then, it will calculate the area of circle as per the formula. The output of Python area fo a circle is

`````` Please Enter the radius of a circle: 6
Area Of a Circle = 113.04
Circumference Of a Circle = 37.68``````

## Python Program to find Area Of Circle using Circumference

Distance around the circle is called as circumference. If you know the circumference then we can calculate the area of a circle using formula: A= C²⁄ 4π (Here C is circumference)

```import math

circumference = float(input(' Please Enter the Circumference of a circle: '))
area = (circumference * circumference)/(4 * math.pi)

print(" Area Of a Circle = %.2f" %area)```

Python area of a circle using circumference output

`````` Please Enter the Circumference of a circle: 26
Area Of a Circle = 53.79``````

First, We imported the math library and this supports us to use all the mathematical functions in Python programming. In this Python example we can call the PI value using math.pi

`import math`

Next line of python program allows user to enter the value of a circumference.

`circumference = float(input(' Please Enter the Circumference of a circle: '))`

Using the circumference, this program will calculate the area of circle as per the formula: A= C²⁄ 4π

## Python Program to Calculate Area Of a Circle using Diameter

Distance across the circle passing through the center is called as diameter. If we know the diameter then we can calculate the area of a circle using formula: A=π/4*D² (D is the diameter)

```import math

diameter = float(input(' Please Enter the Diameter of a circle: '))
area1 = (math.pi/4) * (diameter * diameter)
# diameter = 2 * radius

print(" Area of Circle using direct formula = %.2f" %area1);
print(" Area of Circle Using Method 2 = %.2f" %area2)```

This area of a circle program allows user to enter the diameter value. Next, it will calculate the area of circle as per the formula we shown above.

We also mentioned other approach.