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

  • question_answer
    Consider the following statements:
    1. There exists no triangle ABC for which \[\sin A+\sin B=\sin C.\]
    2. If the angle of a triangle are in the ratio \[1:2:3,\]
    Then its sides will be in the ratio \[1:\sqrt{3}:2.\]
    Which of the above statements is/are correct?

    A) 1 only

    B) 2 only

    C) Both 1 and 2

    D) Neither 1 nor 2

    Correct Answer: C

    Solution :

    [c] 1. Given, \[\sin A+\sin B=\sin C\]
    \[a+b=c\]
    \[\left( \because \,\,By\sin e\,law,\frac{\sin A}{a}=\frac{\sin B}{b}=\frac{\operatorname{sinC}}{c}=K \right)\]
    Here, the sum of two sides of \[\Delta ABC\] is equal to the third side, but it is not possible
    (Because by triangle inequality, the sum of the length of two sides of a triangle is always greater than the length of the third side)
    \[\]
    2. Ratio of angles of a triangle
    \[A:B:C=1:2:3\]
    \[A+B+C=180{}^\circ \]
    \[\therefore A=30{}^\circ \]
    \[B=60{}^\circ \]
    \[C=90{}^\circ \]
    the ratio in sides according to sine rule
    \[a:b:c=\sin A:\sin B:\operatorname{sinC}\]
    \[=\sin 30{}^\circ :\sin 60{}^\circ :\sin 90{}^\circ \]
    \[=\frac{1}{2},\frac{\sqrt{3}}{2},1=\frac{1}{2}:\frac{\sqrt{3}}{2}:1\]


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