Question

How many chords can be drawn through 21 points on a circle?

Answer 1

Answer:

Step-by-step explhjjjanation:

(21 * 20)/ (2 * 1 ) = 210 chords

Answer 2

Answer:

210 chords can be drawn.

Step-by-step explanation:

In the question,

Total number of points on a circle = 21

Also,

We know that for the making of a chord we need 2 points in total.

Therefore, selection of 2 points from the 21 points is needed to be done.

So,

Number of possible chords which can be drawn is given by,

$^{21}C_{2}$

So,

$^{21}C_{2}=\frac{21!}{2!19!}=\frac{21\times 20}{2}\\^{21}C_{2}=21\times 10=210$

Therefore, there are total 210 number of possible chords which can be drawn from these points in the circle.