The distance formula calculates the straight-line distance between two points on a coordinate plane. It is derived directly from the Pythagorean theorem — the horizontal and vertical gaps between the points form the two legs of a right triangle.
Find the distance between points (1, 2) and (4, 6).
x₁=1, y₁=2, x₂=4, y₂=6(x₂-x₁) = 3 (y₂-y₁) = 43² = 9 4² = 16d = √(9 + 16) = √25The distance between the two points is exactly 5 units.