Geometry

5. If two sides in a triangle are congruent, then the opposite angles to these sides are congruent
6. the amount of space that a substance or object occupies
9. A line, line segment, ray, or point that cuts a line segment exactly in half
11. a line that splits an angle into two equal angles
12. a proposition that is consistent with known data, but has been neither verified nor shown to be false
14. in the same plane
15. lying in the same straight line

1. Identical in form
2. the continuous line forming the boundary of a closed geometric figure
3. Space between two intersecting lines or surfaces at or close to the point where they meet
4. each angular point of a polygon, polyhedron, or other figure
7. an angle of 90° to a given line, plane, or surface
8. a plane figure with at least three straight sides and angles, and typically five or more
10. a mathematical statement which appears to be true, but has not been formally proven
13. A point in the center joining two points