# Triangles

by
**MrReGlog**

Last updated 8 years ago

** Discipline: **

Math ** Subject: **

Geometry
** Grade:**

5,6,7

Obtuse triangles have one angle that is obtuse. This means it is bigger than 90 degrees while the other two are smaller than 90 degrees.

A right triangle possesses an angle that is exactly 90 degrees (or a right angle). This is demarked with a square in that corner.

Triangles are polygons with 3 sides and 3 angles. When defined by their side lengths there are three types:ScaleneIsoscelesEquilateral

TRIANGLES

Acute triangles have three angles that are all acute. Meaning none are 90 degrees or bigger.

Equilateral:This type of triangle has three sides that are all equivalent. This also means the three angles are equivalent at 60 degrees each.

Isosceles:Where two of the sides are equal. These triangles also have two equivalent angles

Scalene:When all three sides of a triangle are different lengths, also resulting in three different angles.

Online Interactive Triangle Manipulatives

Pythagorean "Proof Without Words"

Triangles can also be defined by their angles. 2 of the angles will always be acute (or smaller than 90 degrees) but as the 3rd angle changes we get:Acute, Obtuse, and Right triangles

Bibliography:Gustavb. (Designer). (2006). Rtriangle. [Web Graphic]. Retrieved from http://upload.wikimedia.org/wikipedia/ commons/thumb/6/6f/Rtriangle.svg/500px-Rtriangle.svg.png Triangle. (2009). Retrieved from http://www.mathopenref.com/triangle.html

LINKS!

Interactive Definition of Triangle

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