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Question
If 20 points are marked on a circle, how many chords can be drawn?
Solution
There are 20 points on a circle.
To draw a chord, 2 points are required.
∴ the number of chords that can be drawn through 20 points on the circle
= 20C2
= `(20!)/(2!18!)`
= `(20 xx 19 xx 18!)/(2 xx 1 xx 18!)`
= 190.
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