A right triangle is a triangle with one right angle^{[1]}. A right angle is an angle at the intersection of two perpendicular lines. The measure of a right angle is 90 °, which is the same as π/2 rad.
These triangles are right triangles.  These shapes are not right triangles. Either they are not triangles, or they do not have one right angle.  


 
Some parts of a right triangle are named more specifically than the names for the same parts of a general triangle. The boundaries of a general triangle are called sides. The sides opposite the right angle of a right triangle is called an hypotenuse, and the other two sides are called the legs of the right triangle. Solving Right TrianglesTo solve a right triangle is to find an unknown value related to the right triangle from known values. There are a number of identities that can be used to solve right triangles:
To solve a right triangle, find an identity in the list above that has all knowns except for one unknown, fill in the know values, then solve for the unknown. In more complicated problems, two equations and two unknowns can be used. Click on the blue dots in manipulative 2 and drag them to change the figure. Click on the 'Show Pythagorean theorem' check box to see an example of solving a right triangle using the Pythagorean theorem. Click on the 'Show trigonometric function' checkbox to see and example of solving a right triangle using a trigonometric function.
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Cite this article as:McAdams, David E. Right Triangle. 5/5/2011. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/r/righttriangle.html.Image Credits
Revision History12/21/2009: Added "References". (McAdams, David E.)11/28/2009: Rewrote article. (McAdams, David E.) 7/11/2007: Initial version. (McAdams, David E.)
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