15 Geometry

1. A straight line from the center to the circumference of a circle or sphere
3. An angle of 90°, as in a corner of a square or at the intersection of two perpendicular straight lines
6. A round plane figure whose boundary (the circumference) is equidistant from a fixed point (the center)
7. An angle that is less than 90°
9. A plane figure with at least three straight sides and angles, and typically five or more
10. A straight line or plane that touches a curve or curved surface at a point, but if extended does not cross it at that point
12. The longest side of a right-angled triangle, opposite the right angle
15. At an angle of 90° to a given line, plane, or surface

2. The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet
4. A straight line passing from side to side through the center of a body or figure, especially a circle or sphere
5. A straight line that cuts a curve in two or more parts
8. An angle that is more than 90° but less than 180°
11. A straight line connecting two points on a curve
13. Lines or planes that are side by side and having the same distance continuously between them
14. Each angular point of a polygon, polyhedron, or other figure