How many chords can be drawn through 21 points on a circle in how many ways can a team of 3 boys and 3 girls be selected from 5 boys and 4 girls?

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

Answer : Number of points=21

⇒n=21

A chord connects circle at two points.

⇒r=2

⇒Number of chords from 21 points= nCr

⇒ nCr= 21C2

⇒21C2=210 chords.

Ans: 210 chords can be drawn through 21 points on a circle.