What's a isosceles triangle?

Isosceles triangle. In geometry, an isosceles triangle is a triangle that has two sides of equal length. Sometimes it is specified as having two and only two sides of equal length, and sometimes as having at least two sides of equal length, the latter version thus including the equilateral triangle as a special case. read more

Statement 1: An isosceles triangle's altitude, or line segment that extends from the triangle's apex to its base's midpoint, is perpendicular to its base. This part of the theorem is true because an isosceles triangle's congruent sides place its apex (point A) directly over the base's midpoint (point D). read more