Q41 / 90 · JEE Main 2021 (16 Mar Shift 2) · Mathematics

Consider a rectangle ABCD having 5,6,7,9 points in the interior of the line segments AB, BC, CD, DA respectively. Let α be the number of triangles having these points from different sides as vertices and β be the number of quadrilaterals having these points from different sides as vertices. Then β-α is equal to

  • A
    795
  • B
    1173
  • C
    1890
  • Correct answer
    D
    717

Solution

Figure

α= Number of triangles

α=5·6·7+5·7·9+5·6·9+6·7·9

=210+315+270+378

=1173

β= Number of Quadrilateral

β=5·6·7·9=1890

β-α=1890-1173=717

Hence, the correct answer is option: 'D'.

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