Saved Bookmarks
| 1. |
If the sides of a triangle are in G.P., and its largest angle is twicethe smallest, then the common ratio `r`satisfies the inequality`0A. `0ltrltsqrt(2)`B. `1ltrltsqrt(2)`C. `1ltrlt2`D. none of these |
|
Answer» Correct Answer - B Let the sides of the triangle be `a//r`, a and ar, with `agt0gtandrgt1`. Let `alpha` be the smallest angle, so that the largest angle is `2alpha`. Then, `alpha` is opposite to the side `a//r and2alpha` is opposite to the side ar. Applying sine rule, we get `(a//r)/(sinalpha)=(ar)/(sin2alpha)` `rArr" "(sin2alpha)/(sinalpha)=r^(2)` `rArr2cosalpha=r^(2)` `rArr" "r^(2)lt2" "[becausealpha!=:.2cosalphalt2]` `rArr" "rltsqrt(2)` Hence, `1ltrltsqrt(2)` |
|