In similar figures, the ratios of corresponding sides are equal.
Given the sides of the small quadrilateral:
- One side = 2
- Opposite side = 5
For the big quadrilateral:
- Corresponding side to 2 = 3.6
- Corresponding side to 5 = x (which we want to find)
Using the ratio of the corresponding sides, we have:
\[ \frac{2}{3.6} = \frac{5}{x} \]
Now we can cross-multiply to solve for \( x \):
\[ 2x = 3.6 \cdot 5 \]
Calculating the right side:
\[ 3.6 \cdot 5 = 18 \]
So, we have:
\[ 2x = 18 \]
Now, divide both sides by 2:
\[ x = \frac{18}{2} = 9 \]
Therefore, the value of \( x \) is \( \boxed{9} \).