20/11/02 17:00:59.94 nV+GRV6y.net
>>476
PA=a, PB=b, PC=c のとき
PD = √(aa-bb+cc) = d,
{l - (bb-aa)/l}^2 + {m - (cc-bb)/m}^2 = (2a)^2, …… (1)
l^2 - ((bb-aa)/l)^2= m^2 - ((cc-bb)/m)^2, ……Max条件 (2)
(1) (2)から l,m を求めると
l = (ad+bc)/√(aa+cc),
m = (ab+cd)/√(aa+cc),
点Pの座標 (x,y) は
x = {l - (bb-aa)/l}/2 = ad/√(aa+cc),
y = {m - (cc-bb)/m}/2 = ab/√(aa+cc).