9th Class Mathematics Triangles Question Bank Triangles

  • question_answer
    In the given figure, PQR is an equilateral triangle and QRST is a square. Then\[\angle PSR=\_\_\_\_.\]          

    A) \[{{30}^{o}}\]

    B)        \[{{15}^{o}}\]

    C)                    \[{{90}^{o}}\]

    D)        \[{{60}^{o}}\]

    Correct Answer: B

    Solution :

    \[\angle PRS=({{90}^{o}}+{{60}^{o}})={{150}^{o}}\] \[RQ=PR\]  ?(i)                         [Sides of equilateral\[\Delta \]] and \[RQ=RS\]   ?(ii)    [Sides of square] \[\therefore \]\[RP=RS\]               [from (i) and (ii)] \[\Rightarrow \]\[\angle RPS=\angle RSP=x\] In \[\Delta PSR,\angle PRS+\angle SPR+\angle RSP={{180}^{o}}\] \[\Rightarrow \]\[{{150}^{o}}+x+x={{180}^{o}}\] \[{{150}^{o}}+x+x={{180}^{o}}\] \[2x={{30}^{o}}\Rightarrow x={{15}^{o}}\]


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