WBJEE · Maths · Straight Lines
A plane meets the co-ordinate axes at the points \(A, B, C\) respectively in such a way that the centroid of \(\triangle A B C\) is \(\left(1, r, r^{2}\right)\) for some real \(r\). If the plane passes through the point \((5,5,-12)\) then \(r=\)
- A \(\frac{3}{2}\)
- B 4
- C \(-4\)
- D \(-\frac{3}{2}\)
Answer & Solution
Correct Answer
(C) \(-4\)
Step-by-step Solution
Detailed explanation
Centroid is \(\mathrm{G}(\mathrm{a} / 3, \mathrm{~b} / 3, \mathrm{c} / 3) \equiv\left(1, \mathrm{r}, \mathrm{r}^{2}\right)\) \(a / 3=1 \quad \Rightarrow a=3, b=3 r, c=3 r^{2}\) Now,…
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