Geometry

1. Of, at, or forming the center.
3. The middle point of a circle or sphere, equidistant from every point on the circumference or surface.
8. A round plane figure whose boundary consists of points equidistant from a fixed point.
10. Less than 90 degrees
11. The enclosing boundary of a curved geometric figure, especially a circle.
13. The perpendicular distance drawn from the vertex to the opposite side of the triangle.
14. A solid or hollow object which tapers from a circular or roughly circular base to a point.

2. The space between two intersecting lines or surfaces at or close to the point where they meet.
4. Equal in value, amount, function, meaning, etc.
5. Side by side and having the same distance continuously between them.
6. A triangle with three acute angles
7. Ascertain the size, amount, or degree.
9. A part of the circumference of a circle or other curve.
11. A group of notes sounded together, as a basis of harmony.
12. The exact middle point.