Geometry

1. -- a line segment connecting two points of the interior can go outside the polygon; at least one of the interior angles is greater than 180 degrees
2. -- a curve that can be traced without lifting the pencil, has the same starting/stopping points and may cross itself (creates an inside and outside of the curve)
3. -- an angle measuring exactly 90 degrees
5. -- a triangle with three acute angles
9. -- 2-D or 3-D figure having all congruent sides and all congruent angles
10. -- a 3-D geometric figure with an altitude perpendicular to the base(s)
11. -- a cone or cylinder with circles for base(s)
13. -- a 2-D figure; the set of all points at a given distance from the center
14. -- the top and bottom parallel polygonal faces
15. -- the distance from the center to the circle

1. -- the perimeter of a circle
4. -- a parallelogram with a right angle
5. -- an angle measuring between zero and 90 degrees
6. -- a triangle with one right angle
7. -- the height of a 2-D or 3-D geometric figure measured perpendicularly from the center of the top face or point to the center of the base
8. -- the point in the middle of the circle or sphere
12. -- a quadrilateral with four congruent sides