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mathmath333

  • one year ago

On a board having 18 rows and 16 columns ,find the number of rectangles ?

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  1. mathmath333
    • one year ago
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    \(\large \color{black}{\begin{align} & \normalsize \text{ On a board having 18 rows and 16 columns ,find the number}\hspace{.33em}\\~\\ & \normalsize \text{ of rectangles ?}\hspace{.33em}\\~\\ \end{align}}\)

  2. imqwerty
    • one year ago
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    23256

  3. mathmath333
    • one year ago
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    18C2*16C2 ?

  4. imqwerty
    • one year ago
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    theres a formula to find it :D number of rectangles in an m x n grid can be given by - \[\frac{ m(m+1)n(n+1) }{ 4 }\]

  5. mathmath333
    • one year ago
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    no i want methos i cant remeber formula

  6. mathmath333
    • one year ago
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    *method,*remember

  7. imqwerty
    • one year ago
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    ok then try finding out the solution this way- How many ways can I draw two horizontal lines and two vertical lines through an array of (m+1) by (n+1) dots?

  8. mathmath333
    • one year ago
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    lol m confused

  9. mathmath333
    • one year ago
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    m+1C2*n+1c2

  10. imqwerty
    • one year ago
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    (Think of the dots formed at the corners of the little squares within the rectangle)

  11. imqwerty
    • one year ago
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    The two horizontal lines can be drawn C(m+1,2) ways, and the two vertical lines can be drawn C(n+1,2) ways, so the total number of rectangles within an m x n rectangle isC(m+1,2) C(n+1,2)

  12. mathmath333
    • one year ago
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    m+1C2*n+1C2 is correct ?

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