If the length of the chord of the circle x2 + y2 = r2 along the line y - 2x = 3 is r, then r2 is equal to

The length of the chord of the circle x2 + y2 = r2 along the line y = mx + c is given by     2r21+m21+m2−c2Here, m = 2 and c = 3. Therefore,             r=2r2(1+4)−91+4⇒ r=25r2−95⇒5r2=20r2−36⇒r2=3615=125