Geometry

2. a plane figure with at least three straight sides and angles, and typically five or more.
3. (of angles) having a common vertex and a common side
9. If two figures can be placed precisely over each other
10. the enclosing boundary of a curved geometric figure, especially a circle
11. having all its sides of the same length
14. a four-sided plane figure with opposite sides parallel
15. a straight line passing from side to side through the center of a body or figure, especially a circle or sphere

1. two angles whose sum is 90 degrees
4. the highest point; the top or apex
5. (of a triangle) having two sides of equal length
6. (of a triangle) having sides unequal in length
7. a four-sided figure
8. two angles whose sum is 180 degrees
12. the space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet
13. a straight line from the center to the circumference of a circle or sphere