Isosceles triangles have two equal sides and two equal angles.
Triangles are shapes with three sides and three internal angles that always add up to 180 degrees. An isosceles triangle is a specific type of triangle that has certain parameters related to the lengths of its sides and the size of its angles. Its line of symmetry has unique properties that do not exist in other types of triangle.
Name
The name isosceles originated in the mid-18th century. It comes from the Greek word isoskeles, which is made up of two words: isos, meaning equal, and skelos, meaning leg. The complete word means having two sides of equal length. This is the defining property of an isosceles triangle.
Sides
Any triangle that has two or more sides of equal length is an isosceles triangle. The third side can be shorter or longer than the two that are the same. It can even be equal to them; an equilateral triangle is one that has three equal sides and is a special case of an isosceles triangle. When an isosceles triangle is drawn, it is usually the base of the triangle that is different in length.
Angles
An isosceles triangle has two equal angles as well as two equal sides. If the base of the triangle is the longer or shorter side, then the two base angles are equal. Another way to find which of the three angles inside the triangle are equal is to find the equal sides, which you can usually do by eye. It is the angles opposite these sides that are equal. All three angles in the special case of an equilateral triangle are the same.
Symmetry
Unless they are also equilateral, isosceles triangles have only one plane of symmetry. If the triangle is arranged so that the side of different length is the base, a line drawn from the top point of the triangle to the midpoint of the base is the triangle's line of symmetry. One unique property of isosceles triangles is that the line of symmetry is also the bisector of the angle between the two equal sides and perpendicular bisector of the base. A bisector is a line that cuts something in half, and a perpendicular bisector is a line at right angles to the thing it is cutting in half.
Related Posts:
Interesting Facts Triangles In Math
An isosceles triangle has two sides of equal length.A triangle is a three-sided polygon that has three vertices, or corners. Triangles are commonly used in construction to create supporting struct...
Identify Triangles
Identify TrianglesA triangle is a three-sided polygon. Knowing the rules and relationships between the various triangles helps to understand geometry. More importantly, for the high school student...
Identify Triangles By Angles
Part of the tools used to measure the angles of the triangle.A triangle is a basic figure used in Euclidean geometry. A triangle is a two-dimensional figure having three corners or vertices. It is...
Make A Rectangle Using 3 Triangles
A rectangle has four sides and four right angles.Geometry is the study of points, lines and objects, and one large part of this discipline is understanding shapes. A rectangle is defined as a four...
Triangles Used In Architecture
Triangles have a major role in architecture.Geometry and architecture are two disciplines that are fundamentally linked. One of the most recognized geometric shapes is the triangle. Triangles are...
