# Python Program To find Area Of Circle

Write a python program to find the area of a circle using radius, circumstance, and diameter. The area of a circle is the number of square units inside the circle. The 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 the formula: A=πr² (Here, A is the area of the circle, and r is the radius). In this program, we will find the area of a circle using a radius.

```# 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 a global variable and assigned the value as 3.14. This python program allows users to enter the value of a radius. And then, it will calculate the area of a circle as per the formula. The output of the example 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 the circumference. If you know the circumference, then we can calculate the area of a circle using the 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)```

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, which supports us in using all the mathematical functions in Python programming. In this Python example, we can call the PI value using math.pi

`import math`

The next line of the python program allows the 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 a circle as per the formula: A= C²⁄ 4π.

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

The distance across the circle passing through the center is called the diameter. If we know the diameter, then we can calculate the area of a circle using the 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 program allows the user to enter the diameter value. Next, it will calculate the area of a circle as per the formula shown above.

We also mentioned another approach.