Let L1 be the length of the common chord of the curves x2 + y2 = 9 and y2 =8x, and L2 be the length of the latus rectum of y2 = 8x, then

For the points of intersection of the curves x2+y2=9 and y2=8x, we have  x2+8x−9=0⇒x=−9 or x=1 Since x>0 for y2 = 8x, the points of intersection are  (1,22) and (1,−22) so that the length of the common chord L1 is 42.L2=length of the latus rectum of  y2=8x is 8 . So L1