Question

To get to school, you need to walk 9 blocks south and then 12 blocks east. What's the diagonal distance from the start.

Answer 1

Ah -- good old Pythagoras!

a^2 + b^2 = c^2

9^2 + 12^2 = c^2

81 + 144 = c^2

225 = c^2

15 = c

Answer 2

15 blocks