| A | B |
|---|
| acute angle | An angle whose measure is less that 90 degrees. |
| obtuse angle | An angle whose measure is more than 90 degrees. |
| right angle | An angle whose measure is exactly 90 degrees. |
| complementary angles | Two angles whose sum is 90 degrees. |
| supplementary angles | Two angles whose sum is 180 degrees. |
| adjacent angles | Two angles that share a common side. |
| vertical angles | Two angles that are formed by two intersecting lines. |
| non-adjacent angles | Two angles that do not share a common side. |
| straight angle | An angle whose measure is 180 degrees. |
| angle | A figure formed by joining two rays. |
| vertex | The point where two rays intersect to form an angle. |
| protractor | An instrument used to measure angles. |
| congruent angles | Angles that have the same measure. |
| angle bisector | A ray that divides an angle into two congruent angles. |
| alternate interior angles | pairs of angles formed by two lines and a transversal making a "z" pattern |
| transversal | a line that intersects two other lines |
| corresponding angles | pairs of angles formed by two lines and a transversal making an "f" pattern |
| co-interior angles | pairs of angles inside two lines on the same side of the transversal that make a "c" pattern |
| parallel lines | two lines that never intersect |
| right triangle | a triangle with one right angle |
| acute triangle | a triangle whose angles all measure less than 90 degrees |
| obtuse triangle | a triangle that contains one obtuse angle |
| scalene triangle | a triangle with no sides congruent |
| isosceles triangle | a triangle with two congruent sides |
| equilateral triangle | a triangle with three congruent sides |
| perpendicular lines | two lines that form four right angles |
| parallel lines | two lines that never meet |
| line segment | a part of a line with two endpoints |
| ray | a part of a line with one endpoint |
| vector | a directed line segment that has direction and length |
| midpoint | the halfway point on a line segment |
