| A | B |
|---|
| Altitude | The line segment extending from any vertex of a triangle perpendicular to the line containing the opposite side. |
| Straight Angle | An angle that is the union of opposite rays. |
| Median | The line segment extending from any vertex of a triangle intersecting the midpoint of the opposite side. |
| Line Bisector | A line that divides a line segment into two congruent segments. |
| Complementary Angle | Two angles whose sum equals 90 degrees. |
| Perpendicular Bisector | Two lines that form a right angle and intersect at their midpoints. |
| Congruent Triangles | Triangles whose corresponding angles and sides are congruent. |
| Vertical Angles | Two nonadjacent angles formed by two intersecting lines. |
| Adjacent Angles | Angles that share a common vertex, a common side, and no common interior points. |
| Perpendicular Lines | Two lines that form a right angle. |
| Supplementary Angle | Two angles whose sum equals 180 degrees. |
| Acute Angle | An angle whose degree measure is greater than 0 and less than 90. |
| Obtuse angle | An angle whose degree measure is greater than 90 and less than 180. |
| Angle | A set of points that is the union of two rays having the same endpoint. |
| Right Angle | An angle whose degree measure is 90. |
| Collinear Set of Points | It is a set of points all of which lies on the same straight line. |
| Midpoint | It is a point of that line segment that divides the segment into two congruent segments. |
| Point | It may be represented by a dot on a piece of paper, and is usually named by a capital letter. |
| Ray | It is a part of a line that consists of a point on the line,called an endpoint, and all the points on one side of a point. |
| Angle bisector | A ray whose endpoint is the vertex of the angle and which divides the angle into two congruent angles. |
