Isosceles triangle

The isosceles triangle, or isot, is a type of triangle with two of the three side lengths equal, as are two of the three angles. It can be considered as a pyramid where the base is a dyad.

Its unequal side is often called its base, in analogy to the pyramid construction. Its equal sides are called its legs.

Vertex coordinates
Coordinates for an isosceles triangle with base length b and leg length ℓ are given by:
 * (±b/2, 0),
 * (0, $\sqrt{ℓ^{2}–b^{2}/4}$).

In vertex figures
All prisms have an isosceles triangle for a vertex figure.