In this section we will reviewing Triangle basics. You will be using this knowledge about triangles throughout this course. Let's begin with what a triangle is.
A triangle is a polygon that has exactly three sides. All triangles have an interior angle sum of 180 degrees. Triangles are named by their sides and their angles. |
Below are the types of triangles; the first three are by side and the other three are by angle. A triangle can a combination of both; for example, you can have a right isosceles triangle or an obtuse scalene. Triangles can also be equiangular. If a triangle is equilateral then it is also equiangular. A triangles angles coincide with its sides; if a triangle has two congruent angles then it also has two congruent sides. If a triangle has three congruent angles, then it has three congruent sides. If a triangle has no congruent sides then it does not have any congruent angles.