PHP Program to find the Area and Circumference of the circle


October 21, 2023, Learn eTutorial
1844

How to find the Area and Circumference of the Circle, given radius

The area of a circle means the total area which is enclosed by the circle shape. The circumference or perimeter of a circle is the total length of the curve of the circle.

To find the area of a circle first, we have to know the radius of the circle and use the formula 

Area = pi r

  • where 'r' is the radius of the circle
  • pi is a constant and its value is 3.14

To find the circumference or perimeter of a circle, we use the formula 

Circumference = 2 pi r.

  • r is the radius of the circle
  • pi is a constant whose value is 3.14

For example, if the radius of the circle is 7 then the area of the circle will be π * 72 which will be 153.938. The circumference or the perimeter will be 2 * π * 7 which will be 43.982. 

How to find the area and circumference using PHP

In this PHP program, we are using the built-in functions

  • pi() for the pi(3.14) 
  • pwo() to find the power of the value
  • round() to limit the number of digits after the decimal point.

First, we have to read the radius from the user and assign it to a variable, and to find the area we have to use the formula

Area = pi() * pow(radius, 2) 

To find the circumference or perimeter we have to use the formula

circumference or Perimeter = 2 * pi() * radius

ALGORITHM

STEP 1: Accept the radius from the user and assign it to a variable radius

STEP 2: Calculate the area using formula  'pi() * pow(radius, 2)' and assign it to the variable area

STEP 3: Calculate the circumference using formula  '2 * pi() * radius' and add that value to variable circumference

STEP 4: Print the values of the variable 'area' and 'circumference' as the area and circumference of the circle

PHP Source Code

                                          <?php
$radius = readline("Enter the radius: ");
$area = pi() * pow($radius, 2);      // pow() is used to find the power
$area = round($area, 3);            // round() is used to limit the number of digit after the decimal
$circumference = 2 * pi() * $radius;
$circumference = round($circumference, 3);
echo (" Area of circle is $area \n Circumference of the circle is $circumference");
?>
                                      

OUTPUT

Enter the radius: 15
Area of circle is 706.858
Circumference of the circle is 94.248