The radius of the circle represented by the equation 3x^2+3y^2+( … - Vidyadip

MCQ

The radius of the circle represented by the equation $3\text{x}^2+3\text{y}^2+(\lambda-6)\text{y}+3=0$ is:

✓
$\frac{3}{2}$
B
$\frac{\sqrt{17}}{2}$
C
$\frac{2}{3}$
D
None of these

✓

Answer

Correct option: A.

$\frac{3}{2}$

The equation of the circle is $3\text{x}^2+3\text{y}^2+(\lambda-6)\text{y}+3=0$
$\therefore$ Coefficient of $\text{xy}=0$
$\Rightarrow\lambda=0$
$\therefore3\text{x}^2+3\text{y}^2+9\text{x}-6\text{y}+3=0$
$\Rightarrow\text{x}^2+\text{y}^2+3\text{x}-2\text{y}+1=0$
Therefore, the radius of the circle is $\sqrt{\Big(\frac{3}{2}\Big)^2+(-1)^2-1}=\frac{3}{2}.$

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