SOLUTION: Points are marked on a circle, and chords are drawn joining all the points. 1 point - 0 chords 2points - 1 chord 3 ponts - 3 chords find an expression for the number of ch

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Points are marked on a circle, and chords are drawn joining all the points. 1 point - 0 chords 2points - 1 chord 3 ponts - 3 chords find an expression for the number of ch      Log On


   

Question 188752: Points are marked on a circle, and chords are drawn joining all the points.
1 point - 0 chords
2points - 1 chord
3 ponts - 3 chords
find an expression for the number of chords if there are n points on the circle.
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
for each of the n points, a chord can be drawn to each of the other n-1 points

BUT .... a chord from A to B is the same as a chord from B to A, so half of the chords are duplicates

so the number of chords for n points is ... [n * (n-1)] / 2