Question

If there are 10 points on a circle how many chords can be drawn

Answer 1

on a circle,there can be 5 chords formed by 10 points

Answer 2

If there are 10 points on the circle 45 chords can be drawn.

• The number of points on the circle is 10.
• To draw a chord in a circle , 2 points are necessary.
• We have to select any 2 points on the circle from the 10 points to draw a chord.
• That is combination of 10 different points taken 2 at a time.

Number of chords that can be drawn= $^{10}C_2$

Number of chords that can be drawn= $\frac{10!}{(8!)(2!)}$

Number of chords that can be drawn= (10×9) / 2 = 45