How this calculation works
Use Brahmagupta’s formula for a quadrilateral with all vertices on a circle.
THE FORMULA
Area = √[(s−a)(s−b)(s−c)(s−d)]A worked example
Four sides of length 4 give a cyclic square with area 16.
Good to know
Side lengths alone do not fix the area of a general quadrilateral.
Reference: OpenStax Algebra and Trigonometry, Trigonometric Applications (opens in a new tab) ↗
Read the result
Use Brahmagupta’s formula for a quadrilateral with all vertices on a circle.
The primary result is labeled “Area”. Keep the input definitions in view when comparing this result with another method.
Try a related calculation
Side lengths alone do not fix the area of a general quadrilateral.
For a related exercise, try the circle calculator.
A few questions, answered
How can I check the default inputs by hand?
Four sides of length 4 give a cyclic square with area 16.
Which rule does this calculator apply?
Area = √[(s−a)(s−b)(s−c)(s−d)]