With usual notations, if the angles $A, B, C$ of a $\triangle A B C$ are in A.P. and $b: c=\sqrt{3}:…
With usual notations, if the angles $A, B, C$ of a $\triangle A B C$ are in A.P. and $b: c=\sqrt{3}: \sqrt{2}$,
then $\angle \mathrm{A}=$
- $55^{\circ}$
- $45^{\circ}$
- $35^{\circ}$
- $75^{\circ}$
Solution
Since $A, B, C$ are in A.P., $2 B=A+C \Rightarrow B=60^{\circ}$
We know that, $\frac{\sin B}{b}=\frac{\sin C}{c} \Rightarrow \sin C=\frac{C}{b} \times \sin 60^{\circ}$
$\therefore \sin C=\frac{\sqrt{2}}{\sqrt{3}} \times \frac{\sqrt{3}}{2}=\frac{1}{\sqrt{2}}$
$\therefore \quad C=45^{\circ} \Rightarrow A=180^{\circ}-\left(60^{\circ}+45^{\circ}\right)=75^{\circ}$
Asked in: MHT CET 2020 (19 Oct Shift 2)
Practice more Properties of Triangles questions on Aicharya