Question

A set of 4 parallel lines intersect with 5 parallel lines.How many parallelograms are formed

Answer 1

Answer:

4C2 * 5C2 = 60

Step-by-step explanation:

Consider in general m parallel lines are intersecting n parallel lines.

To form a parallelogram two parallel lines must intersect two parallel lines.

Hence the number of parallelograms that are formed when m parallel lines intersect n parallel lines is mC2 x nC2.

Now 4 parallel lines are intersecting another set of 5 parallel lines. Number of parallelograms formed = 4C2 x 5C2 = 6(10) = 60