A circle touches the y-axis at the point (0,4) and passes through the point (2,0). Which of the following lines is not a tangent to this circle?
(A)3x−4y−24=0
(B)3x+4y−6=0
(C)4x−3y+17=0
(D)4x+3y−8=0✓ Correct
Answer: (D)
Solution
Touching the y-axis at (0,4) places the centre at (h,4) with radius h. Passing through (2,0) gives (2−h)2+16=h2, that is 20−4h=0, so h=5; the circle is centred at (5,4) with radius 5. A line is tangent when its distance from the centre equals 5. For 4x+3y−8=0 that distance is 5∣20+12−8∣=524, which is not 5, so this line is not a tangent.
JEE Main · 2020 · 09 Jan 2020 · Shift 1 · Single correct option