Algebra⏱ 4 min read

Distance Formula

d = √((x₂−x₁)² + (y₂−y₁)²)

📖 What is the Distance Formula?

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.

d = √((x₂-x₁)² + (y₂-y₁)²)

🔤 What Each Variable Means

d
DistanceThe straight-line length between the two points
x₁, y₁
First point coordinatesThe x and y values of the starting point
x₂, y₂
Second point coordinatesThe x and y values of the ending point

📝 Step-by-Step Example

Find the distance between points (1, 2) and (4, 6).

1
Label the coordinatesx₁=1, y₁=2, x₂=4, y₂=6
2
Calculate the differences(x₂-x₁) = 3    (y₂-y₁) = 4
3
Square each difference3² = 9    4² = 16
4
Add and take the square rootd = √(9 + 16) = √25
Answer: d = 5 units

The distance between the two points is exactly 5 units.

🧮 Interactive Calculator

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🎯 Quick Fact

The distance formula works in 3D too! Just add a third term: √((x₂-x₁)² + (y₂-y₁)² + (z₂-z₁)²)