Library Home || Full Table of Contents || Library Help
|Jim Wilson, Dept. of Mathematics Education, Univ. of Georgia|
|Problem: Develop a proof for Brahmagupta's Formula, which provides the area A of a cyclic quadrilateral (i.e., a simple quadrilateral inscribed in a circle) with sides of length a, b, c, and d as A = sqrt((s-a)(s-b)(s-c)(s-d)) where s is the semiperimeter (a+b+c+d)/2. There are alternative approaches to this proof. The one outlined here is intuitive and elementary; a more elegant approach is available using trigonometry. From a course on Problem Solving in Mathematics.|
|Resource Types:||Course Notes|
|Math Topics:||Conic Sections and Circles, Triangles and Other Polygons, Trigonometry|
© 1994- The Math Forum at NCTM. All rights reserved.