| A | B |
|---|
| Triangle | A three sided polygon |
| Scalene Triangle | a triangle with no sides congruent |
| Isosceles Triangle | a triangle with at least two sides congruent |
| Equilateral Triangle | a triangle with three congruent sides |
| acute Triangle | A triangle with all acute angles |
| Obtuse Triangle | A triangle with exactly one obtuse angle |
| Right Triangle | A triangle with exactly one right angle |
| equiangular | A triangle with all angles congruent |
| Hypotenuse | The side opposite the right angle in a right triangle |
| Legs of an isosceles triangle | The congruent sides of an isosceles triangle |
| Base angles | The angles on the base of an isosceles triangle, not the vertex angle |
| Angle sum Theorem | The sum of the measures of the 3 angles of a triangle is 180 |
| Third angle theorem | If two angles of two triangles are congruent then the third angles are congruent |
| Exterior angle Theorem | The measure of an exterior angle of a triangle is equal to the sum of the measures of the 2 remote interior angles |
| Exterior angle | Angle formed by one side of a triangle and another side extended |
| remote interior angles | the interior angles of the triangle not adjacent to a given exterior angle |
| corollary | a statement that can easily be proven using a theorem (part of a theorem) |
| Corollary - The acute angles of a right triangle are ____________ | complementary |
| Corollary - There can be at most one ________ angle or ________ angle in a triangle | right, obtuse |
| auxiliary line | a line added to a diagram to help in a proof |
| parallel postulate | If there is a line and a point not on that line, there is exactly one line through the point parallel to the given line. |
| CPCTC | Corresponding parts of congruent triangles are congruent |
| Def. of congruent triangles | Triangles are congruent if and only if their corresponding parts are congruent |
| Name 4 ways to prove triangles congruent | ASA, SSS, SAS, AAS |
| Isosceles triangle theroem | If two sides of a triangle are congruent then the angles opposite those sides are congruent |
| Converse of the isosceles triangle theorem | If two angles of a triangle are congruent then the sides opposite them are congruent |
| A triangle is equilateral if and only if... | it is equiangular |
| Each angle of an equilateral triangle measures... | 60 degrees |
