>130
⇔ {sinh(t)}^2・[ 1+2{sinh(t)}^2 ]=1 ⇔ [2{sinh(t)}^2 -1][{sinh(t)}^2 +1]=0
⇔ sinh(t)=±√(1/2) ⇔ cosh(t)=√(3/2).

AB = |cosh(t)sinh(t) + cosh(t)/sinh(t)| = (3/2)√3.

の希ガス