# What does isosceles mean in geometry?

Jan 7, 2016

The word "isosceles" is, mostly, used referring to triangles with two sides equal in length

#### Explanation:

Here are major properties of isosceles triangles.

Draw altitude $h$ from the vertex where two congruent sides $b$ and $b$ intersect.
It divides our triangle into two right triangles that share a cathetus $h$ and have congruent hypotenuses $b$ and $b$.

These triangles are congruent by cathetus and hypotenuse and, therefore altitude $h$ is also a median of base $a$ and an angle bisector of the angle at the top.

Consequently, two angles at the base of this isosceles triangle are also congruent.