Across
1
Math using letters for unknown values
4
Steepness of a line
6
Space between two intersecting lines
7
Divisible by two
8
Value that does not change
10
Total distance around a shape
11
Corner point of a polygon
12
Longest side of a right triangle
Down
2
Three-sided polygon
3
Power to which a number is raised
4
Result of addition
5
Exact correspondence on both sides
9
Part of a circle's circumference
13
Proven mathematical statement