Final answer:
The area of triangle ABC is 54 cm².
Step-by-step explanation:
To find the area of triangle ABC, we can use the formula for the area of a triangle: Area = 1/2 * base * height. In this case, the base is 12 cm and the height is 9 cm. Plugging in these values, we get: Area = 1/2 * 12 cm * 9 cm = 54 cm². Therefore, the area of triangle ABC is 54 cm².