Properties
The unequal side of an isosceles triangle is usually referred to as the 'base' of the triangle.
The base angles of an isosceles triangle are always equal. In the figure above, the angles ∠ABC and ∠ACB are always the same
When the 3rd angle is a right angle, it is called a "right isosceles triangle".
The altitude is a perpendicular distance from the base to the topmost vertex.