2 A figure formed when three noncollinear points are connected by segments is a triangle. Each pair of segments forms an angle on the triangle.
3 The vertex of each angle is a vertex of the triangle
4 ABC Triangles are named by the letters of their vertices. How you name a triangle by its verticesABC
5 Triangles can be classified by their angles Triangles can be classified by their angles. All triangles have at least two acute angles. The third angle is either acute, obtuse, or right.
6 Triangles can also be classified by their sides.
7 All angles of an equilateral triangle are congruent, at least two are of its sides are congruent. Meaning all equilateral triangles are also isosceles triangles.
8 Parts of an isosceles triangle Parts of an isosceles triangle. Angles formed by the congruent sides is called the vertex angle. The congruent sides are called legs. The side opposite the vertex angle is called the base. The two angles by the base and one of the congruent sides are called based angles.