Geometry

3. equal distances.
4. all its sides of the same length.
5. plane figure with four straight sides and four right angles, especially one with unequal adjacent sides, in contrast to a square.
9. term used to describe a topographic eminence
12. point of intersection between the three perpendicular bisectors of the triangle's sides
13. point where all three altitudes of the triangle intersect
15. centre point of the object
17. quadrilateral with only one pair of parallel sides.
18. a line that splits an angle into two equal angles

1. equal angles
2. plane figure with four equal straight sides and four right angles.
6. four-sided plane rectilinear figure with opposite sides parallel.
7. center of the incircle of a triangle or other fig
8. the middle number in a sorted list of numbers
10. line segment that is drawn from a vertex to the opposite side bisecting the side at a right angle
11. parallelogram with opposite equal acute angles, opposite equal obtuse angles, and four equal sides.
14. toy consisting of a light frame with thin material stretched over it, flown in the wind at the end of a long string.
16. a straight line joining two opposite corners of a square, rectangle, or other straight-sided shape.