The circle possessing $y$-axis as its tangent at $(0,2)$ and passing through $(-1,0)$, also passes through

The circle possessing $y$-axis as its tangent at $(0,2)$ and passing through $(-1,0)$, also passes through
  1. $\left(\frac{-3}{2}, 0\right)$
  2. $\left(\frac{-5}{2}, 2\right)$
  3. $\left(\frac{-3}{2}, \frac{5}{2}\right)$
  4. $(-4,0)$

Solution

Let $(h, k)$ be centre of circle. Circle touches the $y$-axis $\therefore$ Radius of circle $=\mathrm{h}$ Equation of cicle $ (\mathrm{x}-\mathrm{h})^2+(\mathrm{y}-\mathrm{k})^2=\mathrm{h}^2 . $ It passes through $(0,2)$ $ \therefore \mathrm{h}^2+(2-\mathrm{k})^2=\mathrm{h}^2 \Rightarrow \mathrm{k}=2 $ Since, it also passes through $(-1,0)$ $ \therefore(-1,-h)^2+2^2=h^2 \Rightarrow \mathrm{h}=-5 / 2 $ $\therefore$ Equation of circle: $\left(x+\frac{5}{2}\right)^2+(y-2)^2=\left(\frac{5}{2}\right)^2$ Only option (d) $(-4,0)$ satisfied it

Asked in: AP EAMCET 2022 (06 Jul Shift 1)

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