"Maths Language Puzzle": HTML5 Crossword

Across

4. An area of a circle enclosed by a chord (0,7)
6. The longest side of a right-angled triangle. (0,10)
9. Has only two factors (0,5,6)
10. Every other one in a sequence (0,9)
11. The distance across a circle which passes through the centre. (0,8)
12. It has 4 sides where 2 sides are parallel and the other 2 are not (0,9)
14. Find the difference (0,8)
17. A number multiplied by itself (0,7)
18. A part of circumference between and including 2 endpoints on the circle (0,3)
19. The average of a set of numbers (0,4)
20. Describes Angles between 0 and 90 degrees (0,5)

Down

1. Order of operation (0,6)
2. The result of dividing one number by another (0,8)
3. A ten-sided polygon (0,7)
5. Two or more lines which meet at right angles. (0,13)
7. The length of the distance around the boundary of a shape (0,9)
8. Volume is the space occupied inside a 3D object (0,6)
13. A negative or positive whole number (0,7)
15. To divide into two equal parts (0,6)
16. is a line that touches the circumference of the circle at only one point (0,7)