Geometry

4. A continuous extent of length.
7. An equilateral parallelogram having oblique angles.
8. A straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.
9. A quadrilateral having both pairs of opposite sides parallel to each other.(Note: squares and rectangles are also quadrilaterals.)
11. 90 degree angle.
12. A quadrilateral plane figure having two parallel and two nonparallel sides.
15. The line segment between two points on a given curve.
17. The part of a straight line considered as originating at a point on the line and as extending in one direction from that point.
18. Two sides are equal.
19. A position in space.
20. The intersection point of two sides of a plane figure.
21. The largest possible circle that can be drawn interior to a plane figure. For a polygon, a circle is not actually inscribed unless each side of the polygon is tangent to the circle.

1. A polygon having six sides and six angles.
2. A polygon with four sides.(Note: squares, rectangles and trapezoids are also quadrilaterals.)
3. Greater than 90 degrees but less than 180 degrees
5. All sides are equal and all angles equal.
6. The circumcenter of a triangle is the point where the three perpendicular bisectors meet. This point is the same distance from each of the three vertices of the triangles.
10. A parallelogram having four right angles.(Note: a square is also a rectangle.)
11. A straight line extending from the center of a circle or sphere to the circumference or surface.
13. A polygon with 5 sides and 5 angles.
14. A polygon having eight angles and eight sides.
16. A line segment, line, or plane that divides a geometric figure into two congruent halves.