Question

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

Answer 1

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.