Q13 of 68 Page 330

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

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=


⇒21C2=


⇒21C2=


⇒21C2=


⇒21C2=210 chords.


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


More from this chapter

All 68 →
11

How many different teams of 11 players can be chosen from 15 players?

 12

If there are 12 persons in a party and if each two of them shake hands with each other, how many handshakes are possible?

 14

From a class of 25 students, 4 are to be chosen for a competition. In how many ways can this be done?

 1

In how many ways can 5 sportsmen be selected from a group of 10?