Comparison operators are used to compare one value to another.  There are four different ways you can do this:  greater than, less than, equal to, or not equal to.  Each is represented with a different symbol.  Read more about comparison operators.

Boolean logic is a type of decision making that a computer is capable of doing.  It is based on comparing data and operands, and determining if something is true or false.  In boolean everything is true or false, black or white, there is no grey.  Read more about boolean logic.

Given two sides of a right triangle what would you do to calculate the hypotenuse?  There are several ways you can calculate it with PHP, have a look at some more PHP math functions, and then write your own solution to the problem.  Read more.

In this first part of a two part tutorial, we explore how to calculate Pi, how to convert from degrees to radians, and how to calculate the sine, cosine and tangent.  All of these are very useful functions if you need to make geometric calculations.  See the tutorial.