| A | B |
|---|
| height | The distance from a vertex (corner) to the opposite side of a 2-dimensional figure. The base and height are always perpendicular. That is, they always meet at a right or 90˚ angle. |
| right angle | An angle that measures 90˚, like the corner of an index card. |
| parallelogram | A four-sided figure whose opposite sides are parallel and of the same length |
| base | The distance across the bottom of a figure. |
| square units | A square whose sides each measure one unit. Area is measured in square units. |
| area | The measure, in square units, of the space inside a 2-dimensional figure. The shorthand for square units is units2. |
| triangle | A closed figure made from three line segments |
| square | A four-sided figure with all sides the same length and all angles measuring 90˚ |
| rectangle | A four-sided figure with opposite sides the same length and all angles measuring 90˚ |
| perimeter | The distance around the outside of a figure. |
| radius | A line segment from the center of a circle to any point on the circle |
| diameter | A line segment connecting two points on a circle and passing through the circle's center |
| circumference | The length of the perimeter of a circle. Measured in units. |
| pi | For any circle, the ratio of the circumference to the diameter. |
