 # Area of Circle Program in C | What are 2πr and πr2 in Circle

We have a programming challenge to write a program to find the Area of Circle Program in C and Circumference of a Circle in C Language. What is the relation between 2πr and πr2 in Circle? Before going to write a solution in C. We need to know some facts about the circle, Ie. area of circle in c, Radius of Circle, Diameter of Circle, and Circumference of Circle.

We will discuss each point step by step with the help of pictures. What we are going to learn in this article, below is a list.

## Area of Circle and Circumference- Table of Content

• What is Circle
• Diameter of Circle
• How to Calculate Area of Circle in C
• Circumference of Circle
• Explanation of the Problem
• Programming Code in C Language
• The Output of the C Program
• What is Circle

### What is Circle

A circle is a rounded closed shape, with no corner, and no edges. Where all the points in plan are at the same distance from its centre.

### How to Draw a Circle

Radius is the distance from the centre of the circle to any point on its circumference.

### Diameter of Circle

Diameter is nothing but the biggest line in Circle. It’s very easy to calculate the diameter of a circle, just double the radius of the circle. We can find a radius of a circle by the given formula.

Diameter of Circle Formula: Diameter = 2 * Radius.

### How Calculate Area of Circle

The area is a space covered by a circle, Circle area is dependent on its radius. We can calculate the area of the circle by given formula.

### The Formula for Area of Circle

Area of a Circle = πr2 or PI * Radius * Radius.

Here PI value is fixed which is 22/7 or 3.1415926535, but for this problem, we are using a PI value up to 5 decimal digits, If you want to know more about PI click here. You can find the PI value up to 1,00,000 Decimal Digits.

### Area of Circle Circumference

The circumference is a Latin word which means in English “Carrying Around” on in Hindi “परिधि“. The circumference is a fixed or linear distance around it. In other words, we can say that the length of the circle if it were opened up and straightened out to a line segment. THE below GIF clear your all doubts.

### Formula for Circumference of Circle

Circumference of Circle = 2πr or 2 * PI * Radius

## Explanation of Area of Circle Program in C

Now we have both formulas(Area and Circumference), We just need to put the R or Radius value in the both given Formula.

Example 1: Radius of a Circle

Suppose the value of the Radius is 10.5, now put the same value in the formula. We already know the PI value which is 3.14159

area of circle in c = 3.14159 * 10.5 *10.5 = 346.360291

Circumference of Circle = 2πr or 2 * PI * Radius

Circumference of Circle = 2 * 3.14159 * 10.5 = 65.973389

So here is a Final answer is = 346.360291 and Circumference is = 65.973389.

## Area of Circle Program in C & Circumference

``````#include<stdio.h>

int main() {
/* "Area and Circumference of a Circle is C". This Programming Solution belongs to Simple Categories in C Language. -by Tutorials BookMaarks. Visit Here: https://tutorialsbookmarks.com/c-programming-questions-answers-pdf-download/ */
float PI = 3.14159;

printf("Enter the Radius of Circle: ");

printf("\n\narea of circle program in c is = %f ", area_of_circle);
circumference_of_circle = 2 * PI * radius;

printf("\n\nCircumference of Circle is = %f \n", circumference_of_circle);
return (0);
}``````