Across
1
The number representing nothing
3
Proven mathematical statement
5
Sum divided by count
8
Symbol representing unknown value
11
Longest side of a right triangle
13
Divisible by two
Down
2
Line segment connecting two circle points
4
Rectangular array of numbers
6
Space between two intersecting lines
7
Line touching circle at one point
9
Collection of distinct elements
10
Split into equal parts
12
Repeated addition