JEE Main & Advanced Mathematics Triangles & Properties of Triangle Question Bank Self Evaluation Test - Properties of Triangles and Height & Dstances

  • question_answer
    Angles of a triangle are in the ratio \[4:1:1.\] The ratio between its greatest side and perimeter is

    A) \[\frac{3}{2+\sqrt{3}}\]

    B) \[\frac{1}{2+\sqrt{3}}\]

    C) \[\frac{\sqrt{3}}{\sqrt{3}+2}\]

    D) \[\frac{2}{2+\sqrt{3}}\]

    Correct Answer: C

    Solution :

    [c] Consider a triangle ABC.
    Given, angles of a triangle are in the ratio \[4:1:1.\] angles are 4x, x and x
    i.e., \[\angle A=4x,\angle B=x,\angle C=x\]
    Now, by angle sum property of\[\Delta \], we have
    \[\angle A+\angle B+\angle C=180{}^\circ \]
    \[\Rightarrow 4x+x+x=180{}^\circ \Rightarrow x=\frac{180{}^\circ }{6}=30{}^\circ \]
    \[\therefore \angle A=120{}^\circ ,\angle B=30{}^\circ ,\angle C=30{}^\circ \]
    We know, ratio of sides of \[\Delta ABC\]is given by \[\sin A:\sin B:\operatorname{sinC}=sin120{}^\circ :sin30{}^\circ :sin30{}^\circ \]
    \[=\frac{\sqrt{3}}{2}:\frac{1}{2}:\frac{1}{2}=\sqrt{3}:1:1\]
    Required ratio \[=\frac{\sqrt{3}}{1+1+\sqrt{3}}=\frac{\sqrt{3}}{2+\sqrt{3}}.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner