﻿ PHP Exercise: Compute the radius and the central coordinate of a circle - w3resource

# PHP Exercises: Compute the radius and the central coordinate of a circle

## PHP: Exercise-53 with Solution

Write a PHP program to compute the radius and the central coordinate (x, y) of a circle which is constructed by three given points on the plane surface.

Sample Solution: -

PHP Code:

``````<?php
\$x1 = 0; \$y1 = 0; \$x2 = 2; \$y2 = 0; \$x3 = 2; \$y3 = 2;
\$a1 = 2 * (\$x2 - \$x1);
\$b1 = 2 * (\$y2 - \$y1);
\$c1 = \$x1 * \$x1 - \$x2 * \$x2 + \$y1 *\$y1 - \$y2 * \$y2;
\$a2 = 2 * (\$x3 - \$x1);
\$b2 = 2 * (\$y3 - \$y1);
\$c2 = \$x1 * \$x1 - \$x3 * \$x3 + \$y1 *\$y1 - \$y3 * \$y3;
\$x = (\$b1 * \$c2 - \$b2 * \$c1) / (\$a1 * \$b2 - \$a2 * \$b1);
\$y = (\$c1 * \$a2 - \$c2 * \$a1) / (\$a1 * \$b2 - \$a2 * \$b1);
\$r = sqrt((\$x - \$x1) * (\$x - \$x1) + (\$y - \$y1) * (\$y - \$y1));
printf("Central coordinate(x,y) and radius of the circle:\n");
printf("(%.3f %.3f) %.3f\n", \$x, \$y, \$r);
?>
```
```

Sample Output:

```Central coordinate(x,y) and radius of the circle:
(1.000 1.000) 1.414
```

Flowchart:

PHP Code Editor:

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## PHP: Tips of the Day

Mutates the original array to filter out the values specified

Example:

```<?php
function tips_pull(&\$items, ...\$params)
{
\$items = array_values(array_diff(\$items, \$params));
return \$items;
}

\$items = ['x', 'y', 'z', 'x', 'y', 'z'];
print_r(tips_pull(\$items, 'y', 'z'));
?>
```

Output:

```Array
(
[0] => x
[1] => x
)
```