Question: Calculate the area of the trapezoid.
12 mm
5 mm
9 mm
square millimeters
top-center: a trapezoid with top base labeled 12 mm, bottom base labeled 9 mm, and right vertical height labeled 5 mm; the figure is centered in the upper-middle of the page.
User: what is the square millimeters
1. **State the problem:** We need to find the area of a trapezoid with top base $12$ mm, bottom base $9$ mm, and height $5$ mm.
2. **Formula for the area of a trapezoid:**
$$\text{Area} = \frac{(\text{Base}_1 + \text{Base}_2)}{2} \times \text{Height}$$
3. **Substitute the given values:**
$$\text{Area} = \frac{(12 + 9)}{2} \times 5$$
4. **Simplify inside the parentheses:**
$$\text{Area} = \frac{21}{2} \times 5$$
5. **Multiply:**
$$\text{Area} = \frac{21 \times 5}{2}$$
6. **Calculate numerator:**
$$\text{Area} = \frac{105}{2}$$
7. **Divide:**
$$\text{Area} = 52.5$$
8. **Final answer:** The area of the trapezoid is $52.5$ square millimeters.