There are n points on a circle .the number of straight lines obtained by joining these isa)nC3b)nC2c)nC2-1 d)nC1Correct answer is option 'B'. Can you explain this answer?

Question

There are n points on a circle .the number of straight lines obtained by joining these isa)nC3b)nC2c)nC2-1 &#8203;d)nC1Correct answer is option 'B'. Can you explain this answer?

Answer

Consider one particular point So that n -1 straight lines can be drawn from that particular point to the rest . then this gives the permutation as n× n -1 is the permutation of the given situation but in case of a straight line a  line AB and BA both are the same hence we take the combination because here arrangement doesn't matter as we consider the combination we have  that nCr= nPr /r! >>>>>> nC2=np2/2! it comes as we are selecting a minimum of two points to form a straight line because  in case of a circle three points can not form a straight line hence we only consider two points to form a straight line

Answer

Solution:

Each point on the circle can be connected to (n-1) other points, except itself.

Therefore, the number of ways of selecting 2 points from n is nC2.

But each line is counted twice (once for each end), so we need to divide by 2.

Therefore, the number of straight lines obtained by joining n points on a circle is nC2/2.

Hence, option B is the correct answer.

Answer

Hello dear, number of points on a circle=n we can form straight line by joining maximum or minimum 2 points . no of straight line obtained by joining 2 points =nC2 hope it help you

Answer

No three points on a circle can be collinear
Therefore, there can be ⁿC₂ straight lines

Answer

No three points on a circle can be collinear
Therefore, there can be ⁿC₂ straight lines

Answer

One point is not a straight line but when we meet two points then it becomes a straight line so from minimum two is formed a straight line and total number of points are n so we can select minimum two points then answer is 'nC2'

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