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 chord | a line segment joining two points on a curve |
| radius | any line segment connected from the center of a circle to the edge of the circle |
| diameter | any straight line segment that passes through the center of a circle and whose endpoints are on the circle |
| circumference | the distance around a closed curve like a circle |
| similar | two geometrical objects are called similar if they both have the same shape |
| perimeter | the path that surrounds a shape |
| arc | a segment of the circumference of a circle |
| sector | a section of a circle with a radius for each side and the included arc of a circle |
| vertex | a corner or a point where lines meet or the top or high point of something |
| central angle | an angle whose vertex is the center of a circle, and whose sides pass through a pair of points on the circle |
| pentagon | a polygon with 5 sides |
| parallelogram | a quadrilateral with 2 pairs of parallel sides |
| trapezoid | a quadrilateral with 1 set of parallel sides |
| rhombus | a quadrilateral with 4 equal sides (a square is a rhombus with 4 equal sides) |
| quadrilateral | a 4-sided polygon |
| congruent | the same size and shape |
| parallel | parallel lines are two lines in the same plane that never intersect |
| perpendicular | 2 lines that meet at a right angle |
| adjacent | having a common endpoint or border |
| polygon | a closed plane figure, having three or more, usually straight sides |