If a, b, c are in GP and log a - log 2b, log 2b - log 3c and log 3c - log a are in AP, then a, b, c are the lengths of the sides of a triangle which is
The logs are in AP:
\(2(\log 2b - \log 3c) = (\log a - \log 2b) + (\log 3c - \log a) = \log 3c - \log 2b\)
\(3\log 2b = 3\log 3c \Rightarrow 2b = 3c \Rightarrow b = \frac{3c}{2}\)
From the GP, \(b^2 = ac\): \(\frac{9c^2}{4} = ac \Rightarrow a = \frac{9c}{4}\).
So the sides are in the ratio \(a : b : c = 9 : 6 : 4\). Largest side squared: \(81 > 36 + 16 = 52\).
So the triangle is obtuse-angled.
Answer: (B)
Reinforce your conceptual grasp with related questions from MAH MCA CET 2019:
Take timed full-length mock tests with authentic question distributions, negative marking (+12/-3 in Math), and instant All India Rank calculation.
Start Free Mock Test Series →