Find a missing endpoint from one endpoint and midpoint
Result
Missing Endpoint
Step-by-Step Derivation
Endpoint Formula
x₂ = 2mₓ - x₁, y₂ = 2mᵧ - y₁
The endpoint formula reverses the midpoint formula. Since the midpoint is the average of two endpoints, doubling the midpoint coordinate and subtracting the known endpoint gives the missing coordinate.
⚠Enter one known endpoint and the midpoint. The result is the other endpoint of the same segment.
How Endpoint Calculation Works
A midpoint sits exactly halfway between two endpoints. The missing endpoint is found by reflecting the known endpoint across the midpoint.
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