Find the distance between the points (0, 5) and (−5, 0).

Correct answer: 5√2. Distance = √[(−5 − 0)² + (0 − 5)²] = √50 = 5√2.

Background: Use the distance formula: √[(x₂ − x₁)² + (y₂ − y₁)²].

• 4: 4 is not √50.
• 6: 6 is not √50.
• 7: 7 is not √50.

Did you know? It comes from the Pythagorean theorem.

Memory trick: Square the differences, add, root.