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The Number of Diagonals that Can Be Drawn by Joining the Vertices of an Octagon is (A) 20 (B) 28 (C) 8 (D) 16

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Question

The number of diagonals that can be drawn by joining the vertices of an octagon is

Options

  •  20

  • 28

  •  8

  • 16

MCQ
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Solution

20
An octagon has 8 vertices. 
The number of diagonals of a polygon is given by

\[\frac{n \left( n - 3 \right)}{2}\] .
∴ Number of diagonals of an octagon =  \[\frac{8 \left( 8 - 3 \right)}{2} = 20\]
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Chapter 17: Combinations - Exercise 17.5 [Page 26]

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R.D. Sharma Mathematics [English] Class 11
Chapter 17 Combinations
Exercise 17.5 | Q 22 | Page 26

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