Q78 / 155 · WBJEE 2020 · Mathematics

The equation of circle of radius $\sqrt{17}$ unit, with centre on the positive side of $x$ -axis and through the point $(0,1)$ is

  • Correct answer
    A
    $x^{2}+y^{2}-8 x-1=0$
  • B
    $x^{2}+y^{2}+8 x-1=0$
  • C
    $x^{2}+y^{2}-9 y+1=0$
  • D
    $2 x^{2}+2 y^{2}-3 x+2 y=4$

Solution

Hint: Let centre be $\equiv(a, 0)(a>0)$ So, circle : $(x-a)^{2}+y^{2}=17 ;$ as it passes through $(0,1)$, so $a^{2}+1=17 \quad \Rightarrow a=4(a \neq-4, a>0)$ $\therefore$ Equation is : $x^{2}+y^{2}-8 x-1=0$

Hence, the correct answer is option: 'A'.

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