posted by Becky .
If two planes leave the same airport at 1:00 PM, how many miles apart will they be at 3:00 PM if one travels directly north at 150 mph and the other travels directly west at 200 mph?
I understand that d = sqrt[300^2 + 400^2]
d = sqrt[250,000]
But im not sure how you get 500 from this point don't remember!! I used a calculator for [300^2 + 400^2] but not sure how to do the rest?