Q92 / 180 · COMEDK 2017 · Mathematics
Let $(3,4,-1)$ and $(-1,2,3)$ be the end points of a diameter of a sphere. Then, the radius of the sphere is equal to
- A2 units
- Correct answerB3 units
- C6 units
- D7 units
Solution
Let $P(3,4,-1)$ and $Q(-1,2,3)$ be the end points of the diameter of a sphere.
$\therefore$ Length of diameter $=P Q$
$\begin{aligned}
&=\sqrt{(-1-3)^{2}+(2-4)^{2}+(3+1)^{2}} \\
&=\sqrt{16+4+16}=\sqrt{36}=6 \text { units } \\
\therefore \quad \text { Radius } &=\frac{6}{2}=3 \text { units }
\end{aligned}$
Hence, the correct answer is option: 'B'.