How many parallelograms are formed by a set of 4 parallel lines intersecting another set of 7 parallel lines?
We have two sets of parallel lines. Assuming that the two sets are not parallel to each other, we can say that some parallelograms will be formed. We need to determine the number of parallelograms.
If we take any two lines from each of the set a parallelogram will be formed. Hoping that you know the concept of permutations and combination i would like to give the solution of it.