Since, join of (2, 0) and (0, 3) subtends 90° at (0, 0). ⇒ It is a diameter
∴ Equation is (x−2)(x−0)+(y−0)(y−3)=0 x2+y2−2x−3y=0 (2k, 3k) lies on it ⇒4k2+9k2−4k−9k=0 ⇒13k2=13k ⇒k=1 Since, k ≠0 otherwise (2k, 3k) will be (0, 0).