Geometry

5. are often described in terms of two points or referred to using a single letter.
6. a pair of adjacent angles formed when two lines intersect
7. a part of a line that has a fixed starting point but no end point.
9. if one has the same shape and size as the mirror image of the other.
10. a primitive notion that models an exact location in the space, and has no length, width, or thickness
11. a set of points in space
12. if they add up to 90 degrees.
13. a point where two straight lines or rays meet.
14. the term has been used for aligned objects, that is, things being "in a line" or "in a row"
16. a part of a line that is bounded by two distinct end points, and contains every point on the line that is between its endpoints.

1. two angles or arcs whose sum is 180 degrees.
2. the division of something into two equal or congruent parts, usually by a line
3. a line or ray that divides an angle into two congruent angles
4. a pair of non-adjacent angles formed when two lines intersect.
8. two angles that have a common side and a common vertex (corner point) but do not overlap in any way.
10. is a flat, two-dimensional surface that extends infinitely far.
15. the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle