Brahmagupta’s formula

If a cyclic quadrilateral has sides $p,q,r,s$ then its area is given by

$$\sqrt{(T-p)(T-q)(T-r)(T-s)}$$

where $T=\frac{p+q+r+s}{2}$.

Note that if $s\to 0$, Heron’s formula is recovered.

Title	Brahmagupta’s formula
Canonical name	BrahmaguptasFormula
Date of creation	2013-03-22 11:44:19
Last modified on	2013-03-22 11:44:19
Owner	drini (3)
Last modified by	drini (3)
Numerical id	11
Author	drini (3)
Entry type	Theorem
Classification	msc 51-00
Classification	msc 81T70
Classification	msc 81T25
Classification	msc 81T20
Classification	msc 81T75
Classification	msc 81T05
Classification	msc 11-02
Classification	msc 05-02
Classification	msc 05C30
Related topic	CyclicQuadrilateral
Related topic	HeronsFormula