There are mathematical formulas to find the area and circumference of the circle. To find the area of a circle first we have to get the radius of the circle and use the formula πpi r2 and to find the circumference we use the formula 2&pi r. 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 and circumference will be 2 * π * 7 which will be 43.982.
In PHP there are many ways to find the area and circumference of the circle in this program we are using the built-in functions pi() for the pi(3.14) value and pwo() to find the power of the value and we are also using the 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 pi() * pow(radius, 2) and to find the circumference we have to use the formula 2 * pi() * radius.
ALGORITHM Step 1: Accept the radius from the user and assign it to a variable radius
Step 2: Compute the operation to find the area 'pi() * pow(radius, 2)' and assign the value to the variable area
Step 3: Compute the operation to find the circumference '2 * pi() * radius' and assign the value to the variable circumference
Step 4: Print the values of the variable area and circumference as the area and circumference of the circle
<?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");
?>
Enter the radius: 15 Area of circle is 706.858 Circumference of the circle is 94.248
