| A | B |
|---|
| A triangle with all three congruent sides | Equilateral Triangle |
| A triangle with two congruent sides | Isosceles Triangle |
| A triangle with no congruent sides (all of the sides are different) | Scalene Triangle |
| A triangle with all three angles congruent | Equiangular Triangle |
| A triangle with all angles acute | Acute Triangle |
| A triangle with one right angle | Right Triangle |
| A triangle with one obtuse angle | Obtuse Triangle |
| The two congruent segments in an isosceles triangle | Leg (Isosceles Triangle) |
| The two segments that form the right angle in a right triangle | Leg (Right Triangle) |
| The two angles opposite the congruent segments of an isosceles triangle (base angles) are congruent | Base Angles Theorem |
| If the hypotenuse and one leg of a right triangle are congruent to the hypotenuse and one leg of another right triangle, then the triangles are congruent. | Hypotenuse Leg Theorem (or HL |
| c^2 = a^2 + b2 | Pythagorean theorem |
| AB = (square root of: (x1-x2)squared +(y1-y2) squared ) | Distance Formula |
| The segment of a triangle from a vertex to the midpoint of the opposite side | Median |
| The intersection of the three medians of a triangle | Centroid |
| The sum of the interior angles of a triangle is 180 degrees | Triangle Sum Theorem |
| A triangle’s exterior angle is the sum of the opposite two interior angles | Exterior Angles Theorem |
| The sum of the two smaller segments of a triangle must be greater than the third side | Triangle Inequality |
