Across
1
Distance from center to edge of circle
4
U-shaped curve of a quadratic function
5
Round shape with all points equidistant
7
Symbol representing unknown value
8
Exact correspondence on both sides
10
Three-sided polygon
Down
2
Total distance around a shape
3
Rectangular array of numbers
6
System of ordered marks for measuring
9
Single numeral from 0 to 9