Geometry words

2. an angle of 90°
7. a pair of adjacent, supplementary angles, any two angles whose measures sum to 180 degrees.
9. a statement to be proven
10. two rays that have the same endpoint and extend in opposite directions.
15. an angle which is greater than 90° and less than 180°
16. set of two opposite operations
17. an obvious geometric truth that is accepted without proof
18. created when the hypothesis and conclusion are reversed.
20. a plane figure with six straight sides and angles.

1. a line that passes through two lines in the same plane at two distinct points.
3. the enclosing boundary of a curved geometric figure, especially a circle.
4. a four-sided plane rectilinear figure with opposite sides parallel.
5. the exact middle point
6. the line segment from a vertex to the midpoint of the opposite side.
8. a general proposition not self-evident but proved by a chain of reasoning; a truth established by means of accepted truths.
11. a line that splits an angle into two equal angles
12. a straight line that makes the right angle (90 degrees) with the other line.
13. the amount of space occupied by a two-dimensional figure
14. a flat surface or area that extends infinitely in two dimensions and has no thickness.
19. a plane figure with eight straight sides and eight angles.