The Pythagorean Theorem can be stated:
If a triangle is a right triangle, then a2 + b2 = c2, where a and b represent the lengths of the legs of the right triangle, and c represents the length of the hypotenuse.
The converse of the Pythagorean Theorem, then, can be stated:
Converse of the Pythagorean Theorem
If the sum of the squares of the lengths of two sides of a triangle is equal to the square of the length of the third side, then the triangle is a right triangle.
Watch the video below.
Source: http://youtu.be/auK6zXrNVN4, yourteachermathhelp, You Tube
Journal Entry: How can you use the converse of the Pythagorean Theorem to show that a triangle is a right triangle? How might people such as engineers, architects, and landscape designers find this to be useful?