To find the missing measurement (the bottom side), we can use the formula for the area of a rectangle:
\[ \text{Area} = \text{length} \times \text{width} \]
In this case, we are given:
- Area = 81 in²
- One side (right side) = 9 in
- The missing side (bottom) is what we need to find.
We can rearrange the formula to solve for the bottom side:
\[ \text{bottom} = \frac{\text{Area}}{\text{right side}} \]
Substituting the known values:
\[ \text{bottom} = \frac{81 \text{ in}^2}{9 \text{ in}} = 9 \text{ in} \]
Now we round the answer to the nearest tenth, although in this case, the answer is already a whole number:
\[ \text{bottom} = 9.0 \text{ in} \]
From the options provided, the measurement that matches this result is:
9 in