x²/a²-y²/b²=1离心率c/a,实轴2a,虚轴2b,焦距2c设等差数列c/a,2a,2b,2c的公差为d则有离心率c/a,实轴c/a+d,虚轴c/a+2d,焦距c/a+3d即a=(c/a+d)/2,b=(c/a+2d)/2,c=(c/a+3d)/2a²+b²=c²...