Hi, 11 parallel lines are intersected by another 9 parallel lines.Then how many parallelograms are formed?
Name : Moorthy
With warm Regards Hi Moorthy, There is a simple way to count: A unique parallelogram will be formed by any two lines from the first set, and any two lines from the second set. So count the ways of choosing 2 lines from 11 (order does not matter) AND choosing 2 lines from 9 (order does not matter). Since this is an AND (we must do both) you multiply those two numbers to get the numbers of parallelograms Walter Whiteley
