The equation to the circle with centre (2, 1) and touching the line 3x + 4y = 5 is
i.e., ∣∣∣3.2+4.1−5√9+16∣∣∣ ⇒∣∣6+4−55∣∣=1
∴ circle is (x−2)2+(y−1)2=1 x2+y2−4x−2y+4=0.