Tamil Nadu Board of Secondary EducationHSC Commerce Class 11

How many chords can be drawn through 21 points on a circle? - Business Mathematics and Statistics

Advertisements
Advertisements
Sum

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

Advertisements

Solution

To draw a chord we need two points on a circle.

∴ Number chords through 21 points on a circle = 21C2 = `(21xx20)/(2xx1) = 210`

Concept: Combinations
  Is there an error in this question or solution?
Chapter 2: Algebra - Exercise 2.4 [Page 38]

RELATED QUESTIONS

If nPr = 1680 and nCr = 70, find n and r.


Out of 7 consonants and 4 vowels, how many words of 3 consonants and 2 vowels can be formed?


If four dice are rolled, find the number of possible outcomes in which atleast one die shows 2.


There are 18 guests at a dinner party. They have to sit 9 guests on either side of a long table, three particular persons decide to sit on one side and two others on the other side. In how many ways can the guests to be seated?


If a polygon has 44 diagonals, find the number of its sides.


How many code symbols can be formed using 5 out of 6 letters A, B, C, D, E, F so that the letters

  1. cannot be repeated
  2. can be repeated
  3. cannot be repeated but must begin with E
  4. cannot be repeated but end with CAB.

The value of n, when np2 = 20 is:


The number of ways selecting 4 players out of 5 is


The number of diagonals in a polygon of n sides is equal to


The number of parallelograms that can be formed from a set of four parallel lines intersecting another set of three parallel lines is:


If `""^15"C"_(2"r" - 1) = ""^15"C"_(2"r" + 4)`, find r


Prove that `""^35"C"_5 + sum_("r" = 0)^4 ""^((39 - "r"))"C"_4` = 40C5


A Kabaddi coach has 14 players ready to play. How many different teams of 7 players could the coach put on the court?


There are 15 persons in a party and if each 2 of them shakes hands with each other, how many handshakes happen in the party?


A trust has 25 members. How many ways 3 officers can be selected?


How many different selections of 5 books can be made from 12 different books if, Two particular books are never selected?


There are 5 teachers and 20 students. Out of them a committee of 2 teachers and 3 students is to be formed. Find the number of ways in which this can be done. Further find in how many of these committees a particular teacher is included?


In an examination a student has to answer 5 questions, out of 9 questions in which 2 are compulsory. In how many ways a student can answer the questions?


Determine the number of 5 card combinations out of a deck of 52 cards if there is exactly three aces in each combination


A committee of 7 peoples has to be formed from 8 men and 4 women. In how many ways can this be done when the committee consists of at most 3 women?


A box contains two white balls, three black balls and four red balls. In how many ways can three balls be drawn from the box, if at least one black ball is to be included in the draw?


How many triangles can be formed by joining 15 points on the plane, in which no line joining any three points?


Choose the correct alternative:
The number of ways in which a host lady invite 8 people for a party of 8 out of 12 people of whom two do not want to attend the party together is


Choose the correct alternative:
The number of parallelograms that can be formed from a set of four parallel lines intersecting another set of three parallel lines


Choose the correct alternative:
Number of sides of a polygon having 44 diagonals is ______


Choose the correct alternative:
In a plane there are 10 points are there out of which 4 points are collinear, then the number of triangles formed is


Choose the correct alternative:
`""^(("n" - 1))"C"_"r" + ""^(("n" - 1))"C"_(("r" - 1))` is


Choose the correct alternative:
The number of ways of choosing 5 cards out of a deck of 52 cards which include at least one king is


Choose the correct alternative:
The number of rectangles that a chessboard has ______


Share
Notifications



      Forgot password?
Use app×