| image | | The point where the three medians of a triangle intersect |
| transitive property | | A shape that results from a transformation of a figure known as the preimage |
| parallelogram | | The relationship between figures having the same shape and same size |
| congruence | | A point at an end of a segment or a starting point of a ray |
| square | | Lying in the same plane |
| equilateral triangle | | A statement that is accepted as true without proof |
| trapezoid | | A point where the edges of a figure intersect |
| acute triangle | | A statement using "if and only if" |
| hypothesis | | A polygon in which all angles are congruent |
| vertex | | For any real number (a, a=a) |
| angle bisector | | A line, ray, or segment that intersects two or more coplaner lines, rays, or segments, each at a different point |
| centroid | | Abbreviation for "corresponding parts of congruent triangles are congruent" |
| theorem | | A quadrilateral with one and only one pair of parallel sides |
| conjecture | | A triangle with three acute angles |
| coplanar | | Two angles in a plane that share a common vertex and a common side but have no interior points in common |
| endpoint | | A statement that has been proven to be true deductively |
| transversal | | A figure formed by two rays with a common endpoint |
| biconditional | | A triangle in which all three sides are congruent |
| acute angle | | The pharse following the word if in a conditional statement |
| obtuse angle | | A quadrilateral with two pairs of parallel sides |
| angle | | A quadrilateral with four congruent sides and four right angles |
| reflexive property | | A ray that divides an angle into two congruent angles |
| collinear | | An angle whose measure is greater than 90 degrees |
| equilateral polygon | | A segment from a vertex to the midpoint of the opposite side in a triangle |
| CPCTC | | Lying on the same line |
| median | | For all real numbers (a,b, and c, if a=b and b=c then a=c) |
| equiangular polygon | | A polygon in which all sides are congruent |
| vertical angles | | The opposite angles formed by two intersectingg lines |
| rectangle | | An angle whose measure is less than 90 degrees |
| adjacent angles | | A quadrilateral with four right angles |
| postulate | | A statement that is believed to be true |
