Across
1
Symbol representing unknown value
5
Distance from center to edge of circle
6
Round shape with all points equidistant
9
Three-sided polygon
12
Line touching circle at one point
Down
2
Repeated addition
3
Mathematical statement of equality
4
Number with digits after a point
7
Mathematical rule or equation
8
Number less than zero
10
Lines that never intersect
11
Total distance around a shape