The number of parallelograms that can be formed from a set of five par...
Understanding the Problem
To determine the number of parallelograms formed by two sets of parallel lines, we need to understand how these lines intersect.
Components of the Problem
- **First Set of Lines**: 5 parallel lines
- **Second Set of Lines**: 3 parallel lines
Forming a Parallelogram
A parallelogram is formed by selecting two lines from the first set and two lines from the second set. The selected lines from each set must be non-parallel to each other to ensure the shape is a parallelogram.
Calculating Combinations
1. **Selecting Lines from the First Set**:
- We can choose 2 lines from 5 parallel lines.
- The number of ways to choose 2 lines from 5 is given by the combination formula \( C(n, r) = \frac{n!}{r!(n-r)!} \).
\[
C(5, 2) = \frac{5!}{2!(5-2)!} = \frac{5 \times 4}{2 \times 1} = 10
\]
2. **Selecting Lines from the Second Set**:
- We can choose 2 lines from 3 parallel lines.
\[
C(3, 2) = \frac{3!}{2!(3-2)!} = \frac{3 \times 2}{2 \times 1} = 3
\]
Total Number of Parallelograms
To find the total number of parallelograms, we multiply the combinations from both sets:
\[
\text{Total Parallelograms} = C(5, 2) \times C(3, 2) = 10 \times 3 = 30
\]
Final Answer
Thus, the total number of parallelograms that can be formed from the given sets of lines is **30**.