QR question

[UnimaasMED]

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How many chords on a circle can be drawn from six distinct points lying on the circle?

Can somebody explain how to go about this type of questions?

 

[dshope]

if you choose any two points and connect them, a chord will form.

so what we are doing is to try to choose 2 points out of the 6 and connect them. Here choosing point A and point B is same as choosing point B and then point A. so we should use combination over permutation

the answer will be 6C2 which is 6!/ 2!4! = 15

 

[UnimaasMED]

if you choose any two points and connect them, a chord will form.

so what we are doing is to try to choose 2 points out of the 6 and connect them. Here choosing point A and point B is same as choosing point B and then point A. so we should use combination over permutation

the answer will be 6C2 which is 6!/ 2!4! = 15

Great explanation👍. I am still a little confused. Don't we use the permutation formula whenever we are looking at a case where order matters? In this case order does not matter right?

 

[DATkiller]

I have the same question. Can anyone explain when order matters and when it doesn't and which formula we have to use in each case?

 

[dshope]

Great explanation👍. I am still a little confused. Don't we use the permutation formula whenever we are looking at a case where order matters? In this case order does not matter right?

you are right the order does not matter that's why combination (C) was used instead of the permuatation (P)

6C2 = 15
6P2 = 30