KVPY Sample Paper KVPY Stream-SX Model Paper-25

  • question_answer
    ABCD is a convex quadrilateral. 3, 4, 5 and 6 points are marked on the sides AB, BC, CD and DA respectively. Find the number of triangles with vertices on different sides.

    A) 215

    B) 342

    C) 225

    D) 424

    Correct Answer: B

    Solution :

    the number of triangles with vertices on sides \[AB,BC,CD={}^{3}{{C}_{1}}\times {}^{4}{{C}_{1}}\times {}^{5}{{C}_{1}}\]Similarly for other cases
    \[\therefore \]The total number of triangles
    \[={}^{3}{{C}_{1}}\times {}^{4}{{C}_{1}}\times {}^{5}{{C}_{1}}\times {}^{3}{{C}_{1}}\times {}^{4}{{C}_{1}}\times {}^{6}{{C}_{1}}\]\[+{}^{3}{{C}_{1}}\times {}^{5}{{C}_{1}}\times {}^{6}{{C}_{1}}+{}^{4}{{C}_{1}}\times {}^{5}{{C}_{1}}\times {}^{6}{{C}_{1}}=342\]


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