Geometry · Coordinate Geometry
Distance Formula
HSG-GPE.B.7
Definition
d = square root of (x2 - x1) squared plus (y2 - y1) squared, the distance between two points.
Examples
- From (0,0) to (3,4): d = square root of (9 + 16) = square root of 25 = 5.
- From (1,1) to (4,5): d = square root of (9 + 16) = square root of 25 = 5.
Key rule
The distance formula comes directly from the Pythagorean theorem.
Memory hook
It's the Pythagorean theorem, applied to two coordinate points.