Across
1
Symbol representing unknown value
4
The number representing nothing
5
Number with digits after a point
6
Number greater than zero
7
Steepness of a line
9
Reference line in a graph
10
Result of addition
12
Line touching circle at one point
Down
1
Amount of space an object occupies
2
Repeated addition
3
Number less than zero
8
Line segment connecting two circle points
11
Three-sided polygon