geotry

6. a part of a line or curve between two points
7. a rule in algebra or other branches of mathematics expressed by symbols or formulae
9. perpendicular line segments from the vertex to the line containing the opposite side
11. opposite or contrary in position, direction, order, or effect
12. a part of a figure cut off by a line or plane intersecting it
13. the point on a line segment or an arc that is equidistant, when measured along the line or arc, from both endpoints
15. any of a set of straight lines passing through one point
16. a 2D shape that has 4 sides, 4 corners, and 4 right angles. Opposite sides of a rectangle are the same length, with one pair longer than the other
17. a line joining the midpoint of two sides of a triangle
18. the distance around the outside of a shape

1. a plane figure with four equal sides and four right (90 degree) angles
2. the line or line segment that divides the angle into two equal parts
3. Angles that measure less than 90 degrees
4. a triangle that has three unequal sides
5. the amount of space within the perimeter of a 2D shape
8. exceeding 90 degrees but less than 180 degrees
10. suggest or assume the existence,fact, or truth of (something) as a basis for reasoning, discussion or belief
14. an angle of 180 degrees