Noticethat the two base angles are also congruent. In an isosceles triangle, if two sides are equal, then the angles opposite to the two sides correspond to each other and are also always equal. The precise statements of the conjectures are: Conjecture (Isosceles Triangle Conjecture I ): If a triangle is isosceles, then the base angles are congruent. Since the right angles are in between these twosides we can see that by side-angle-side, we have two congruent triangles.Thus the two hypotneuses are congruent so we indeed have an isosceles triangle. Equilateral triangles have all equal sides and angles whereas isosceles triangles have only two sides equal and one side can be shorter or longer and a scalene Triangle has all unequal sides. We knowthat the altitude bisects the base so now we have two sides of the two righttriangles are congruent. If we canshow that these two right trianglesare congruent, then we can prove thatthe above triangle is indeed an isosceles triangle. It is the perpendicualrline from the midpoint of the base to the opposite vertex. Definition: An isosceles triangle is defined as a triangle having two congruent sides or two sides that are the same length. In theabove triangle, the red dashed line is called an altitude.

Scroll down for sure-fireways to tell if a triangle is isosceles or not. The triangle to the rightis an isosceles triangle, even though it may be hard to tell. Pei used an isosceles triangle also as the base of the building to accommodate the shape of the plot. In an isosceles triangle, two of thethree sides of the triangle have the same length.