If in a triangle $\mathrm{ABC}$, the altitudes from the vertices $\mathrm{A}, \mathrm{B}, \mathrm{C}$ on…

If in a triangle $\mathrm{ABC}$, the altitudes from the vertices $\mathrm{A}, \mathrm{B}, \mathrm{C}$ on opposite sides are in H.P., then $\sin A, \sin B, \sin C$ are in
  1. G.P.
  2. A.P.
  3. Arithmetic - Geometric Progression
  4. H.P.

Solution

$\Delta=\frac{1}{2} p_1 a=\frac{1}{2} p_2 b=\frac{1}{2} p_3 b$ $p_1, p_2, p_3$ are in H.P. $\Rightarrow \frac{2 \Delta}{a}, \frac{2 \Delta}{b}, \frac{2 \Delta}{c}$ are in H.P. $\Rightarrow \frac{1}{a}, \frac{1}{b}, \frac{1}{c}$ are in H.P $\Rightarrow a, b, c$ are in A.P. $\Rightarrow \sin A, \sin B, \sin C$ are in A.P.

Asked in: JEE Main 2005

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