geometry

1. a type of symmetry which is with respect to reflections
4. a four-sided plane rectilinear figure with opposite sides parallel.
6. a transformation consisting of a translation combined with a reflection about a plane parallel to the direction of the translation.
7. the highest point; the top or apex.
10. two lines that meet or intersect each other at right angles (90°).
12. the action or condition of becoming or being made wider, larger, or more open.
13. when an object is rotated on its own axis, the shape of the object looks the same
15. the throwing back by a body or surface of light, heat, or sound without absorbing it.

2. a measurement of the amount, of namely angle, that a figure is rotated about a fixed point, often the center of a circle.
3. a line midway between something, called a pre-image, and its mirror reflection.
5. the action of rotating around an axis or center.
8. Any way of moving all the points in the plane such that. a) the relative distance between points stays the same and. b) the relative position of the points stays the same.
9. two lines (on the same plane) are parallel to each other if they never intersect each other, ragardless of how far they are extended on either side.
11. the quality of being made up of exactly similar parts facing each other or around an axis.
14. in agreement or harmony.