Across
1
Line segment connecting two circle points
4
Space between two intersecting lines
5
Number that divides evenly into another
10
Proven mathematical statement
11
Three-sided polygon
12
Reference line in a graph
Down
2
Part of a circle's circumference
3
Closed shape with straight sides
6
System of ordered marks for measuring
7
Lines that never intersect
8
Part of a line with two endpoints
9
Line touching circle at one point