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# Types of Triangles Study Guide: GED Math (page 3)

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Updated on Mar 23, 2011

### Similar Triangles

Triangles are similar if they have the same shape and their sizes are proportional to one another. You can prove that two triangles are similar using one of the following three rules. Notice that the symbol ˜ means similar to.

### Parts of a Right Triangle

A triangle that has a right angle is called a right triangle. The sides and angles of right triangles have special relationships.

As you know, a right triangle has three sides. Two of the sides come together to form the right angle. These two sides are called legs. The third side of the triangle is called the hypotenuse. The hypotenuse is always the longest side of a right triangle. It is directly across from the right angle.

### The Pythagorean Theorem

Right triangles are special triangles used for measuring. In a right triangle, the base and one side are perpendicular.

In right triangles, there is a special relationship between the hypotenuse and the legs of the triangle. This relationship is always true and it is known as the Pythagorean theorem. The following equation summarizes the Pythagorean theorem.

a2 + b2 = c2

In the equation, a and b are the legs of the right triangle, and c is the hypotenuse.

In words, the Pythagorean theorem states that in a right triangle, the sum of the squares of the lengths of the legs is equal to the square of the length of the hypotenuse.

Practice problems for these concepts can be found at:

Geometry Practice Problems: GED Math