| A | B |
|---|
| Plane | A flat surface that extends on forever in all directions |
| Angle | Two rays that begin at the same point |
| Vertex | The point at the corner of an angle |
| Ray | Part of a line that has one endoint and extends on forever in one direction |
| Line | Straight path of points that extend forever in opposite directions |
| Congruent | Having the same measure |
| Measure of an angle | Number of degrees in an angle |
| Congruent angles | Angles that have the same measure |
| Acute Angle | An angle less than 90' |
| Right Angle | An angle equal to 90' |
| Obtuse Angle | An angle greater than 90' |
| Straight | A straight line; an angle equal to 180' |
| Complementary | Two angles whose sum is 90' |
| Supplementary | Two angles whose sum is 180' |
| Vertical angles | Angles formed by intersecting lines; they are congruent |
| Perpendicular | Two lines that intersect at right angles |
| Parallel | Two lines in the same plane that never meet |
| Right Triangle | A triangle with one right angle |
| Pythagorean Theorem | Sum of the squares of the measure of the legs of a right triangle is equal to the square of the hypotenuse |
| Legs of a right triangle | Two sides of a right triangle that create the right angle |
| Hypotenuse | The side opposite the right angle in a right triangle; it is always the longest side |
