The video above, from examsolutions.co.uk, does a good job explaining the Pythagorean Theorem and how to use it. The narrator defines many important vocabulary terms, such as hypotenuse, right angle and right triangle.
The Pythagorean Theorem only works with right triangles, but you can use it in many different ways. For example, carpenters use the Pythagorean Theorem with building lines to set out a house foundation to ensure the foundations are square.
The formula a2 + b2 = c2 means (leg)2 + (leg)2 = (hypotenuse)2. The variables a, b and c were randomly chosen to use in the theorem, but you could use any variables you like.
Study and practice
Use these search terms to find your own resources: