| Leg | | a polygon that is both equiangular and equilateral |
| Obtusetriangle | | in a right triangle a side adjacent to the right angle |
| Adjacentangles | | a 6-sided polygon |
| Diameter | | in a right triangle the side opposite the right angle |
| Square | | two angles in a plane that have a common vertex and a common side but no common interior points (2 wds) |
| Skew | | an equation stating that two ratios are equal |
| Pentagon | | a quadrilateral with exactly one pair of parallel sides |
| Similar | | a 4-sided polygon |
| Postulate | | points all in one plane |
| Collinear | | an angle formed by two radii drawn to consecutive vertices (2 wds) |
| Scalene | | the angle formed when one side of a polygon is extended (2 wds) |
| Transversal | | two triangles with congruent angles and corresponding sides in proportion |
| Obtuseangle | | a line that contains a chord |
| Parallelogram | | a line that intersects two or more coplanar lines in different points |
| Angle | | two triangles with sides of equal length and angles of equal measure (2 wds) |
| Straightangle | | the distance from the center of a circle to any of its points |
| Sphere | | a figure formed by two rays that have the same endpoint |
| Triangle | | coplanar lines that do not intersect |
| Polygon | | a triangle with all sides congruent |
| Righttriangle | | two points on a line and all the points between them |
| Circumscribed | | an arc of a circle cut off by the diameter |
| Equilateral | | two angles whose measures have the sum of 90 degrees |
| Diagonal | | a 5-sided polygon |
| Regular | | the figure formed by three segments joining noncollinear points |
| Hexagon | | two angles whose measures have the sum 180 degrees |
| Tangent | | a chord that contains the center of a circle |
| Supplementary | | a triangle with three acute angles |
| Rhombus | | lines that are not coplanar |
| Trapezoid | | a segment whose endpoints lie on a circle |
| Proportion | | a quadrilateral with both pairs of opposite sides parallel |
| Cube | | a circle drawn around a polygon so that each vertex of the polygon lies on the circle |
| Quadrilateral | | a line in the plane that intersects a circle in exactly one point |
| Chord | | any perpendicular segment connecting a vertex to an opposite side |
| Theorem | | a quadrilateral with four right angles |
| Bisector | | a triangle with one obtuse angle (2 wds) |
| Altitude | | an angle with measure between 90 and 180 degrees (2 wds) |
| Exteriorangle | | a rectangular solid with square faces |
| Congruenttriangles | | two angles whose sides form two pairs of opposite rays (2 wds) |
| Midpoint | | two lines that intersect to form right angles (2 wds) |
| Perpendicularlines | | the point that divides the segment into two congruent segments |
| Rectangle | | a quadrilateral with four congruent sides |
| Coplanar | | an angle with measure of 90 degrees (2 wds) |
| Complementary | | a statement that is accepted without proof |
| Hypotenuse | | a line, segment or ray that intersects a segment or angle and forms two congruent segments or angles |
| Isosceles | | a quadrilateral with four right angles and four congruent sides |
| Acute | | a segment from the vertex to the midpoint of the opposite side |
| Centralangle | | the set of all points in space that are a given distance from a given point |
| Verticalangles | | a statement that can be proved |
| Semicircle | | a triangle with at least two congruent sides |
| Segment | | a triangle with no sides congruent |
| Parallel | | a segment joining two non-consecutive vertices of a polygon |
| Median | | points all in one line |
| Rightangle | | a plane figure formed by coplanar segments such that (1) each segment intersects exactly two other segments; and (2) no two segments with a common endpoint are collinear |
| Secant | | an angle with measure of 180 degrees (2 wds) |
| Radius | | segments that have equal length (2 wds) |
| Congruentsegments | | a triangle with one right angle (2 wds) |
