Math Tutor Bob - Pythagorean theorem

Pythagoras, who lived in about 500 BC (that would be about 2500 years ago) is credited with developing the Pythagorean theorem.

There is also evidence that many people were working on the idea at approximately the same time.
Trigonometry is one of the most basic forms of geometry and the Pythagorean Theorem has
many basic uses in modern day.

The theorem can be written as an equation relating the lengths of the sides of a right triangle where c is the length of the hypotenuse and a and b are the other two sides.

a2 + b2 = c2

Or taking the square root of both sides as:

√(a2 + b2) = √c2

And remember that squaring and taking the square root are inverse operations, so:

√(a2 + b2) = c

Remember that the hypotenuse (c) is:

  1. across from the right angle, not touching the right angle in any way
  2. the longest side of the right triangle
  3. substituted for c in the Pythagorean theorem

(ref: wikiHow)

Beyond the above introduction to the theorem, which is really not all that complicated, the key to learning to use it is to do numerous problems. Below are several sites with several problems each:

MathScore

Geometry Practice Page - Oswego School District

Algebra Practice Page - Oswego School District

Patrick on video

Kahn Academy on video

Word Problems (Math Videos Online)