Mathematics Dictionary
Dr. K. G. Shih
Figure 011 : Six points on circle
Q01 |
- Diagram : Six points on circle
Q02 |
- Three points on circle making chords
Q03 |
- Four points on circle making chords
Q04 |
- Five points on circle making chords
Q05 |
- Eleven points on circle making chords
Q01. Diagram :
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Q02. Three points on circle making chords
Question
Three points on circle
How many chords can be drawn ?
Solution
Let 3 points be A, B, C
Two chords : Chords AB, AC
One chord : Chord BC
Total = 1 + 2 = 3
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Q03. Four points on circle making chords
Question
Four points on circle
How many chords can be drawn ?
Solution
Let 4 points be A, B, C, D
Point A : 3 chords AB, AC, AD
Point B : 2 chords BC, BD
Point C : 1 Chord CD
Total = 1 + 2 + 3 = 6
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Q04. Five points on circle making chords
Question
Five points on circle
How many chords can be drawn ?
Solution
Let 5 points be A, B, C, D, E
Point A : 4 chords AB, AC, AD, AE
Point B : 3 chords BC, BD, BE
Point C : 2 Chords CD, CE
Point D : 1 chord DE
Total = 1 + 2 + 3 + 4 = 10
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Q05. Eleven points on circle making chords
Question 1
How manu chords can be made if 11 points are on circle ?
Answer
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55 chords
Question 2
How manu chords can be made if 101 points are on circle ?
Answer
1 + 2 + 3 + 4 + .....+ 96 + 97 + 98 + 99 + 100 = 5050 chords
Question 3
What is the sequence of number of chords : 3, 6, 10, 15 .... ?
Answer
It is triangular number sequence.
nth term is T(n) = n*(n + 1)/2
Sum of n terms S(n) = Sum[n*(n + 1)/2] = n*(n + 1)*(n + 2)/6
Subject |
Prove that Sum[n*(n + 1)/2] = n*(n + 1)*(n + 2)/6
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