Question

In how many ways c an a pair of parallrl diagonlas of regular polyhon of 10 sides be selected

Answer 1

Answer:

The number of ways a pair of parallel diagonals of regular polygon of 10 sides can be selected is 105

Step-by-step explanation:

Number of diagonals of a n sided regular polygon = n(n - 3)/2

Number of diagonals of a 10 sided regular polygon = 10 × (10 - 3)/2

= 35

For a n sided polygon if n is even then the number of parallel diagonal is given by n(n - 4)/4

Therefore, the number of parallel diagonals in 10 sided regular polygon

= 10(10 - 4)/4 = 60/4 = 15

Therefore, the number of ways to select the pair of parallel diagonals

= 15/2

= 15!/13!×2!

= 15×14×13i/2!×13!

= 105

Hope it helps you.....

Answer 2

Answer:

105 is the right answer......