| A | B |
|---|
| Polygon | Closed shape with all straight sides |
| Triangle | 3-sided polygon |
| Quadrilateral | 4-sided polygon |
| Pentagon | 5-sided polygon |
| Hexagon | 6-sided polygon |
| Octagon | 8-sided polygon |
| Right angle | Angle equal to 90 degrees |
| Acute angle | Angle less than 90 degrees |
| Obtuse angle | Angle greater than 90 degrees |
| Line | A string of points that goes on and on in both directions |
| Line Segment | A part of a line with 2 endpoints |
| Ray | A part of a line with 1 endpoint |
| Parallel lines | Lines that never cross or touch |
| Intersecting lines | Lines that cross |
| Perpendicular lines | Intersecting lines that form a right angle |
| Radius | A line segment with one endpoint on the circle and one endpoint in the center |
| Diameter | A line segment with 2 endpoints on the circle that passes through the middle |
| Trapezoid | A quadrilateral with 1 pair of parallel sides |
| Parallelogram | A quadrilateral with opposite sides parallel and congruent |
| Rhombus | A parallelogram with 4 congruent sides |
| Rectangle | A parallelogram with 4 right angles |
| Square | A rectangle with 4 congruent sides |
| Isosceles Triangle | A triangle with 2 congruent sides |
| Equilateral Triangle | A triangle with 3 congruent sides and 3 angles equal to 60 degrees |
| Scalene Triangle | A triangle with 3 sides of different lengths |
| Right Triangle | A triangle with 1 right angle |
| Area | The space inside a shape |
| Perimeter | The distance around the outside of a shape |
| Area of a rectangle | base x height |
| Area of a triangle | 1/2(base x height) |
| Congruence | Same size and same shape |
| Symmetry | to be able to fold in half and have all points and lines match up |
| Vertex | The point where 2 sides of a polygon meet |
