1
Two angles whose measures have the sum of 180 degrees.
2
Two angles whose measures sum 90 degrees.
4
Two lines that intersect forming a right angle.
6
A point on a line segment that divides it into two congruent parts.
9
An equilateral parallelogram .
10
A closed figure in a plane formed by connecting segments end to end, intersecting exactly two others.
11
segment in a triangle that joins a vertex with the midpoint of the opposite side.
