There are three types of triangles, and the area formula works for all of them. You can determine which type of triangle you're looking at by measuring the sides or angles. In an equilateral triangle, all three sides and all three angles are equal. An isosceles triangle has just two equal sides and two equal angles. And in a scalene triangle, all sides and angles are different.
In Greek, "isos-" means "equal", and "skeles" means "leg". So, there will be two congruent/equal sides of the same length, along with two equal angles.
