Question

Find the number of parallelograms that can be formed asset of four parallel lines intersecting another set of three parallel lines

Answer 1

To form a parallelogram, we need two sets of parallel lines.

Selecting two parallel lines from a set of four can be done in 4C2 = 6
Selecting two parallel lines from a set of three parallel lines can be done in 3C2 = 3

Thus number of parallelogram that can be formed is 6×3 = 18

Answer 2

Firstly

No of parallelogram to find= ?

Then , set of parallel lines =4 we know the rule , ie nC2= 4C2= 6

Another set of three parallel lines = 3 again apply the rule ie is = 3

Total no of parallelogram formed from set of parallel lines= 6×3= 18