Advertisements
Advertisements
प्रश्न
If 20 points are marked on a circle, how many chords can be drawn?
Advertisements
उत्तर
There are 20 points on a circle.
To draw a chord, 2 points are required.
∴ the number of chords that can be drawn through 20 points on the circle
= 20C2
= `(20!)/(2!18!)`
= `(20 xx 19 xx 18!)/(2 xx 1 xx 18!)`
= 190.
APPEARS IN
संबंधित प्रश्न
Find the value of `""^20"C"_16 - ""^19"C"_16`
If `""^"n""P"_"r" = 1814400` and `""^"n""C"_"r"` = 45, find r.
If `""^"n""C"_("r" - 1)` = 6435, `""^"n""C"_"r"` = 5005, `""^"n""C"_("r" + 1)` = 3003, find `""^"r""C"_5`.
After a meeting, every participant shakes hands with every other participants. If the number of handshakes is 66, find the number of participants in the meeting.
If 20 points are marked on a circle, how many chords can be drawn?
Ten points are plotted on a plane. Find the number of straight lines obtained by joining these points if no three points are collinear.
Ten points are plotted on a plane. Find the number of straight lines obtained by joining these points if four points are collinear.
Find n if `""^"n""C"_8 = ""^"n""C"_12`
Find n, if `""^21"C"_(6"n") = ""^21"C"_(("n"^2 + 5)`
In how many ways can a boy invite his 5 friends to a party so that at least three join the party?
A group consists of 9 men and 6 women. A team of 6 is to be selected. How many of possible selections will have at least 3 women?
Nine friends decide to go for a picnic in two groups. One group decides to go by car and the other group decides to go by train. Find the number of different ways of doing so if there must be at least 3 friends in each group.
Find n if 2nC3 : nC2 = 52 : 3
Find n and r if nPr = 720 and nCn–r = 120
Find n and r if nCr–1 : nCr : nCr+1 = 20 : 35 : 42
If nPr = 1814400 and nCr = 45, find n+4Cr+3
Find the number of ways of selecting a team of 3 boys and 2 girls from 6 boys and 4 girls
After a meeting, every participant shakes hands with every other participants. If the number of handshakes is 66, find the number of participants in the meeting.
Find the number of diagonals of an n-sided polygon. In particular, find the number of diagonals when n = 15
Ten points are plotted on a plane. Find the number of straight lines obtained by joining these points if four points are collinear
Find the number of triangles formed by joining 12 points if four points are collinear
Find n if nC8 = nC12
Find n if nCn–2 = 15
Find the value of `sum_("r" = 1)^4 ""^((21 - "r"))"C"_4`
A group consists of 9 men and 6 women. A team of 6 is to be selected. How many of possible selections will have at least 3 women?
A question paper has two sections. section I has 5 questions and section II has 6 questions. A student must answer at least two question from each section among 6 questions he answers. How many different choices does the student have in choosing questions?
Five students are selected from 11. How many ways can these students be selected if two specified students are selected?
Select the correct answer from the given alternatives.
A question paper has two parts, A and B, each containing 10 questions. If a student has to choose 8 from part A and 5 from part B, In how many ways can he choose the questions?
Select the correct answer from the given alternatives.
The number of arrangements of the letters of the word BANANA in which two N's do not appear adjacently
Answer the following:
A student finds 7 books of his interest but can borrow only three books. He wants to borrow the Chemistry part-II book only if Chemistry Part-I can also be borrowed. Find the number of ways he can choose three books that he wants to borrow.
Answer the following:
30 objects are to be divided in three groups containing 7, 10, 13 objects. Find the number of distinct ways for doing so.
Answer the following:
Find the number of ways of dividing 20 objects in three groups of sizes 8, 7 and 5
Answer the following:
Four parallel lines intersect another set of five parallel lines. Find the number of distinct parallelograms formed
In how many ways can a group of 5 boys and 6 girls be formed out of 10 boys and 11 girls?
