Using the PHP documentation site explore the documented functions. Share with the class a function and briefly explain its functionality. Include the URL to the function you are sharing. Include an example usage of the function as well.

For example: The PHP runtime includes, among many other things, support for all trigonometric functions including cos, sin, tan and much more.

The cos function is documented here https://www.php.net/manual/en/function.cos.php

cos() returns the cosine of the arg parameter. The arg parameter is in radians.

php echo cos(M_PI); // -1 ?>