Quandaries and Queries 

Name: Dale
Who is asking: Parent
Question: Hi Dale, For the inscribed triangle whose sides are a, b, and c, the nicest way to write the formula for the circumradius R is to use the semiperimiter s = ^{(a+b+c)}/_{2}. Then Although there might be a similar formula for the circumradius of an inscribed quadrangle, I do not recall having seen it. My guess is that it would not be a practical formula. Here is how to compute R using a computer: From this we compute BD = sqrt(a^{2} + b^{2}  2ab cos(A)) Finally, use the triangle formula on the triangle whose sides are a, b, and BD. I see no reason to even think about the formula for the circumradius of an inscribed 5sided polygon. Chris 

