23/08/30 07:55:34.48 pAnGsONQ.net
前>>374
>>382
K:x^2+y^2+z^2=1
S:(x-1/3)^2+(y-1/3)^2+(z-1/3)^2=2/3
T:(x-1/3)^2+(y-1/3)^2+(z-1/3)^2=2/3
円Sの半径は√6/3
q=rのときA(1,0,0)と円Sの中心(1/3,1/3,1/3)について対称な点は、
(2/3)^2+(q-1/3)^2+(q-1/3)^2=2/3
2(q-1/3)^2=2/3-4/9=2/9
(q-1/3)^2=1/3
q-1/3=1/3
q=2/3
(-1/3,2/3,2/3)
pqr=(-1/3)(2/3)(2/3)=-4/27
∴-4/27≦pqr≦0