Across
1
The number representing nothing
3
Amount of space an object occupies
4
Longest side of a right triangle
6
Total distance around a shape
10
Space between two intersecting lines
11
Number with digits after a point
Down
2
Result of multiplication
5
Round shape with all points equidistant
7
U-shaped curve of a quadratic function
8
Value that does not change
9
Number less than zero
12
Exact correspondence on both sides