Question:medium

If a circle with center \((-1,1)\) touches the line \(x+2y+4 = 0\), then the co-ordinates of the point of contact are

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The point of contact is the foot of the perpendicular from the centre to the tangent line.
Updated On: Oct 1, 2026
  • \((-2,-1)\)
  • \((8,-2)\)
  • \((2,-3)\)
  • \((4,-4)\)
Show Solution

The Correct Option is A

Solution and Explanation

Step 1: Use the line through the centre perpendicular to the tangent.
The tangent has direction vector $(2, -1)$, so the normal direction is $(1, 2)$. The perpendicular through $(-1, 1)$ is $(x, y) = (-1 + t, 1 + 2t)$.

Step 2: Intersect with the tangent.
Substitute in $x + 2y + 4 = 0$: $(-1 + t) + 2(1 + 2t) + 4 = 0$, so $5t + 5 = 0$ and $t = -1$.

Step 3: Get the point.
\[ (x, y) = (-1 - 1,\ 1 - 2) = (-2, -1) \]

Step 4: Check the other options.
(B), (C) and (D) do not satisfy the line equation, for instance $8 - 4 + 4 \neq 0$.

Final Answer:
Option (A). \[ \boxed{(-2, -1)} \]
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