10th Class Mathematics Triangles Question Bank Case Based (MCQs) - Triangles

  • question_answer
    Which of the following forms a Pythagoras triplet?

    A) \[(5,11,13)\]

    B) \[(9,15,18)\]

    C) \[(17,24,25)\]

    D) \[(20,21,29)\]

    Correct Answer: D

    Solution :

    According of Pythagoras theorem,
    \[{{(\text{Longest side},\text{ i}.\text{e}.,\text{ hypotenuse)}}^{2}}\]
    \[={{(\text{one side i}\text{.e}\text{.},\text{ base)}}^{2}}+{{(\text{other side i}\text{.e}\text{.},\text{ height)}}^{2}}\]From option ; \[(5,11,13)\]
    Longest side = 13, one side = 5 and other side = 11
    Now, \[{{(11)}^{2}}+{{(5)}^{2}}=121+25=146\]
    and       \[{{(13)}^{2}}=169\]
    \[{{(13)}^{2}}\ne {{(11)}^{2}}+{{(5)}^{2}}\]
    \[(5,11,13)\] does not form a Pythagoras triplet.
    From option ; \[(9,15,18)\]
    longest side =18, one side =9 and other side =15
    Now,   \[{{(15)}^{2}}+{{(9)}^{2}}=225+81=306\]
    and         \[{{(18)}^{2}}=324\]
    \[{{(18)}^{2}}\ne {{(15)}^{2}}+{{(9)}^{2}}\]
    \[\therefore \,\,(9,15,18)\]does not form a Pythagoras triplet.            
    From option ; \[(17,24,25)\]
    longest side =25, one side =17 and other side =24 
    Now,  \[{{(17)}^{2}}+{{(24)}^{2}}=289+576=865\]
    and        \[{{(25)}^{2}}=625\]
                \[{{(25)}^{2}}={{(17)}^{2}}+{{(24)}^{2}}\]
    \[\therefore \,(17,24,15)\] does not form a Pythagoras triplet.        
    From option ; \[(20,21,29)\]
    longest side =29, one side =21 and other side =20
    Now, \[{{(20)}^{2}}+{{(21)}^{2}}=400+441=841\] and \[{{(29)}^{2}}=841\]
                \[{{(29)}^{2}}={{(20)}^{2}}+{{(21)}^{2}}\]
    \[\therefore \,(20,21,29)\] forms a Pythagoras triplet.
    So, option [d] is correct.


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