设C(X1,3/8X1^2),D(X2,3/8X2^2)
CD=(X2-X1,3/8(X2-X1)(X2+X1))
BA=(-8,0)
由题意可知BA=CD
=>X2=4,X1=-4故存在C(-4,6) D(4,6)满足题意