Product of focal distances =(a+ex1)(a−ex1)=a2−e2x12=a2−e2(3)=a2−3e2=47⇒a2=47+3e2⇒4a2=7+12e2&(3,21) lines on a2x2+b2y2=1∴a23+4b21=1 a23+4(a2)(1−e2)1=112(1−e2)+1=4a2(1−e2)13−12e2=(7+12e2)(1−e2)⇒13−12e2=7−7e2+12e2−12e4⇒12e4−17e2+6=0∴e2=2417±289−288=2417±1=43&32∴e=23&32∴ difference ==23−32=233−22