Across
1
Closed shape with straight sides
2
Line crossing from corner to corner
3
Corner point of a polygon
6
Part of a circle's circumference
7
Mathematical statement of equality
8
U-shaped curve of a quadratic function
10
Collection of distinct elements
11
Distance from center to edge of circle
Down
1
Parts per hundred
2
Single numeral from 0 to 9
4
System of ordered marks for measuring
5
Number less than zero
9
Steepness of a line
12
Exact correspondence on both sides