How this calculation works
Find the distance between the centres of the inscribed and circumscribed circles.
THE FORMULA
OI²=R(R−2r)A worked example
R=5 and r=2 give centre distance √5.
Good to know
A triangle must satisfy R≥2r.
Reference: OpenStax Algebra and Trigonometry, Trigonometric Applications (opens in a new tab) ↗
Read the result
Find the distance between the centres of the inscribed and circumscribed circles.
The primary result is labeled “Centre distance”. Keep the input definitions in view when comparing this result with another method.
Try a related calculation
A triangle must satisfy R≥2r.
For a related exercise, try the circle calculator.
A few questions, answered
How can I check the default inputs by hand?
R=5 and r=2 give centre distance √5.
Which rule does this calculator apply?
OI²=R(R−2r)