Across
1
Proven mathematical statement
5
Three-sided polygon
6
Space between two intersecting lines
7
Closed shape with straight sides
13
Single numeral from 0 to 9
14
Total distance around a shape
Down
2
Collection of distinct elements
3
Lines that never intersect
4
Mathematical rule or equation
7
Result of multiplication
8
Comparison of two quantities
9
Symbol representing unknown value
10
Exact correspondence on both sides
11
Middle value in an ordered dataset
12
Difference between highest and lowest values