हिंदी

Write the Number of Parallelograms that Can Be Formed from a Set of Four Parallel Lines Intersecting Another Set of Three Parallel Lines.

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प्रश्न

Write the number of parallelograms that can be formed from a set of four parallel lines intersecting another set of three parallel lines.

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उत्तर

A parallelogram is formed by choosing two straight lines from a set of four parallel lines and two straight lines from a set of three parallel lines.
Two straight lines from the set of four parallel lines can be chosen in 4C2 ways and two straight lines from the set of three parallel lines can be chosen in 3C2 ways.
∴ Number of parallelograms that can be formed =

\[\ ^{4}{}{C}_2 \times \ ^{3}{}{C}_2 = \frac{4!}{2! 2!} \times \frac{3!}{2! 1!} = 6 \times 3 = 18\]

 

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Factorial N (N!) Permutations and Combinations
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अध्याय 17: Combinations - Exercise 17.4 [पृष्ठ २४]

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आर.डी. शर्मा Mathematics [English] Class 11
अध्याय 17 Combinations
Exercise 17.4 | Q 8 | पृष्ठ २४

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