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 answerA$x^{2}+y^{2}-8 x-1=0$
- 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'.