MATH!!!

12345678
Across
  1. 2. A number below 0
  2. 3. A diagram with Quadrilles 1,2 and 3
  3. 6. Its like MPH
  4. 7. only how far a number is from zero
  5. 8. lower than 90 Deg.
Down
  1. 1. A number above 0
  2. 4. More then 90 Deg.
  3. 5. to calculate