Across
1
Value that does not change
4
Split into equal parts
5
Symbol representing unknown value
6
Single numeral from 0 to 9
8
Part of a circle's circumference
9
Closed shape with straight sides
12
Lines that never intersect
Down
2
Distance from center to edge of circle
3
Number that divides evenly into another
4
Line crossing from corner to corner
7
Three-sided polygon
10
Rectangle with four equal sides
11
Space between two intersecting lines
13
Comparison of two quantities