Tangent Length from External Point Calculator
Enter circle radius and center-to-point distance, with the point outside the circle.
A QUICK WALKTHROUGH
How to use this tool
- Enter a positive circle radius.
- Enter a greater center-to-point distance.
- Calculate tangent length.
Right-triangle formula
For radius r and external point distance d>r, tangent length t=√(d²−r²). The radius is perpendicular to the tangent at the contact point.
Ideal geometry
Assumes an ideal circle and an external point in the same plane. Local calculation only.
GOOD TO KNOW
Common questions
Can the point be on or inside the circle?
This calculator excludes d≤r; d=r is a zero-length degenerate case.