Across
1
Math using letters for unknown values
3
System of ordered marks for measuring
4
Longest side of a right triangle
5
Power to which a number is raised
7
Part of a whole number
8
Line segment connecting two circle points
10
Three-sided polygon
13
Single numeral from 0 to 9
Down
2
Line touching circle at one point
3
Steepness of a line
6
Reference line in a graph
9
Sum divided by count
11
The number representing nothing
12
Result of raising a number to an exponent