# Find the unknown side of a Cyclic quadrilateral when d is the diameter or the circle

#### schlynn

1. The problem statement, all variables and given/known data
Given a cyclic quadrilateral with side lengths 1, 2, 3 and d (in that order) where d is the diameter of the circle, find d.

3. The attempt at a solution

I tried using Ptolemy's theorem and Brahmagupta's formula, but to no avail. Can I get pointed in the correct direction please?

#### singular

Re: Find the unknown side of a Cyclic quadrilateral when d is the diameter or the cir

Maybe you can find something useful http://pballew.blogspot.com/2009/10/notes-on-cyclic-quadrilaterals.html" [Broken].

Last edited by a moderator:

### The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving