| A | B |
|---|
| Parallel lines | Coplanar lines that do not intersect |
| Skew lines | noncoplanar lines |
| Parallel planes | planes that do not intersect |
| Transversal | a line that intersects two or more coplanar lines in different points |
| Alternate interior angles | two nonadjacent interior angles on opposite sides of the transversal |
| Same-side interior angles | two interior angles on the same side of the transversal |
| Corresponding angles | two angles in corresponding positions relative to the two lines |
| Same-side interior angles are | supplementary |
| Scalene triangle | no sides congruent |
| Isosceles triangle | at least two sides congruent |
| Equilateral triangle | all sides congruent |
| Vertex | a corner of a triangle |
| Acute triangle | triangle with 3 acute angles |
| Obtuse triangle | triangle with an obtuse angle |
| Right triangle | triangle with a 90 degree angle |
| Equiangular triangle | triangle with all angles equal |
| Auxiliary line | a line added to a diagram to help in a proof |
| Quadrilateral | polygon with four sides |
| Pentagon | polygon with five sides |
| Hexagon | polygon with six sides |
| Octagon | polygon with eight sides |
| Decagon | polygon with 10 sides |
| Regular polygon | polygon with all sides congruent and all angles congruent |
| Sum of exterior angles of a polygon | 360 |
| Sum of measures of the angles of a convex polygon | 180(n-2) |
| Inductive reasoning | conclusion reached based on observation |
| Deductive reasoning | conclusion must be true if hypothesis is true |
