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Triangle - Types of triangles

Triangle - Types of triangles: Encyclopedia II - Triangle - Types of triangles

Triangles can be classified according to the relative lengths of their sides: In an equilateral triangle all sides are of equal length. An equilateral triangle is also equiangular, i.e. all its internal angles are equal—namely, 60°; it is a regular polygon In an isosceles triangle two sides are of equal length. An isosceles triangle also has two equal internal angles (namely, the angles where each of the equal sides meets the third side). In a scalene triangle all sides have different lengths. The internal angles ...

Triangle: Encyclopedia II - Triangle - Types of triangles

Triangle - Types of triangles

Triangles can be classified according to the relative lengths of their sides:

In an equilateral triangle all sides are of equal length. An equilateral triangle is also equiangular, i.e. all its internal angles are equal—namely, 60°; it is a regular polygon
In an isosceles triangle two sides are of equal length. An isosceles triangle also has two equal internal angles (namely, the angles where each of the equal sides meets the third side).
In a scalene triangle all sides have different lengths. The internal angles in a scalene triangle are all different.

Triangles can also be classified according to the size of their largest internal angle, described below using degrees of arc.

A right triangle (or right-angled triangle) has one 90° internal angle (a right angle). The side opposite to the right angle is the hypotenuse; it is the longest side in the right triangle. The other two sides are the legs of the triangle.
An obtuse triangle has one internal angle larger than 90° (an obtuse angle).
An acute triangle has internal angles that are all smaller than 90° (three acute angles).