Across
1
U-shaped curve of a quadratic function
3
Single numeral from 0 to 9
6
Part of a line with two endpoints
7
Steepness of a line
10
Result of addition
11
Space between two intersecting lines
12
Part of a circle's circumference
Down
2
Three-sided polygon
4
Rectangle with four equal sides
5
Longest side of a right triangle
8
Line crossing from corner to corner
9
Corner point of a polygon
10
Exact correspondence on both sides
13
Number less than zero