PHP Program to find the Area and Circumference of the circle


October 21, 2023, Learn eTutorial
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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