"Maths Language Puzzle": HTML5 Crossword

Across

3. A ten-sided polygon (0,7)
4. It has 4 sides where 2 sides are parallel and the other 2 are not (0,9)
6. Find the difference (0,8)
8. A number multiplied by itself (0,7)
9. The longest side of a right-angled triangle. (0,10)
13. Has only two factors (0,5,6)
15. A negative or positive whole number (0,7)
16. The distance across a circle which passes through the centre. (0,8)
17. is a line that touches the circumference of the circle at only one point (0,7)
19. Volume is the space occupied inside a 3D object (0,6)
20. A part of circumference between and including 2 endpoints on the circle (0,3)

Down

1. An area of a circle enclosed by a chord (0,7)
2. Order of operation (0,6)
5. Every other one in a sequence (0,9)
7. Describes Angles between 0 and 90 degrees (0,5)
10. Two or more lines which meet at right angles. (0,13)
11. The length of the distance around the boundary of a shape (0,9)
12. The result of dividing one number by another (0,8)
14. To divide into two equal parts (0,6)
18. The average of a set of numbers (0,4)