Extremities of the latus rectum are (5,10) and (5,-10). Since any circle drawn with any focal chord as its diameter touches the directirx, thus the equations of the required circle is (x−5)2+(y−10)(y+10) = 0
(circle touching the directrix at (- 5,0) which is the foot of the directrix) i.e., x2+y2−10x−75 = 0 Its radius = 10