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If 20 points are marked on a circle, how many chords can be drawn? - Mathematics and Statistics

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Sum

If 20 points are marked on a circle, how many chords can be drawn?

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Solution

To draw a chord we need to join two points on the circle.
There are 20 points on the circle.
∴ We can draw 20C2 chords of the circle.

= `(20!)/((20 - 2)!2!)`

= `(20!)/(18!2!)`

= `(20 xx 19xx18!)/(2xx1xx18!)`

= 190
190 chords can be drawn.

Concept: Properties of Combinations
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APPEARS IN

Balbharati Mathematics and Statistics 2 (Commerce) 11th Standard HSC Maharashtra State Board
Chapter 6 Permutations and Combinations
Exercise 6.6 | Q 10 | Page 90
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