| A | B |
|---|
| Chord | A line segment whose endpoints are on a circle.,  |
| Circumference | The distance around a circle |
| Diameter | A line segment that has endpoints on a circle and passes through the center of the circle.,  |
| Heptagon | A polygon with 7 sides. |
| Hypotenuse | The longest side of a right triangle (which is also the side opposite the right angle).,  |
| Leg (of a right triangle) | Either of the two sides that form the right angle in a right triangle.,  |
| Nonagon | A polygon with 9 sides. |
| Plane | A flat surface that extends infinitely in all directions. |
| Radius | A line segment that has one endpoint on a circle and the other endpoint at the center of the circle.,  |
| Regular polygon | A polygon that has all sides congruent and all angles congruent. |
| Similar polygons | Polygons that have the same shape, but not necessarily the same size. Corresponding sides of similar polygons are proportional. |
| Straight angle | An angle with a measure of 180º |
| Transformation | The moving of a figure by a translation (slide), rotation (turn) or reflection (flip). |
| Acute angle | An angle with a measure less than 90°. |
| Area | The measure, in square units, of the inside of a plane figure. |
| Cone | A solid figure that has a circular base and one vertex. |
| Congruent | Having the same size and shape. |
| Cube | A rectangular solid having six congruent square faces. |
| Cylinder | A three-dimensional figure with two circular bases, which are parallel and congruent. |
| Edge | The line segment where two faces of a solid figure meet. |
| Equivalent | Having the same value. |
| Face | A plane figure that serves as one side of a solid figure. |
| Hexagon | A polygon with 6 sides. |
| Line | A straight path extending in both directions with no endpoints. |
| Line of symmetry | A line that divides a figure into two halves that are mirror images of each other. |
| Line segment | A part of a line with two endpoints. |
| Obtuse angle | An angle with a measure more than 90º. |
| Octagon | A polygon with 8 sides. |
| Parallel lines | Lines that never intersect and are always the same distance apart.,  |
| Parallelogram | A quadrilateral whose opposite sides are parallel and congruent. |
| Pentagon | A polygon with 5 sides. |
| Perimeter | The distance around a figure. |
| Perpendicular lines | Two lines, segments or rays that intersect to form right angles.,  |
| Pyramid | A solid figure with a polygon base and triangular sides that meet at a single point |
| Quadrilateral | A polygon with 4 sides. |
| Ray | A part of a line that has one endpoint and continues without end in one direction. |
| Rectangular prism | A solid figure in which all six faces are rectangles. |
| Reflection (flip) | A transformation that produces the mirror image of a figure.,  |
| Rhombus | A parallelogram with four equal sides. |
| Right angle | An angle that measures exactly 90º. |
| Right triangle | A triangle that has a 90º angle. |
| Rotation (turn) | A movement of a figure that turns that figure around a fixed point.,  |
| Sphere | A solid figure that has all points the same distance from the center.,  |
| Translation (slide) | A movement of a figure to a new position without turning or flipping it.,  |
| Trapezoid | A quadrilateral with exactly one pair of parallel sides. |
| Vertex | A point where lines, rays, sides of a polygon or edges of a polyhedron meet (corner).,  |
| Volume (capacity | The amount of space (in cubic units) that a solid figure can hold. |
