Answer:
422.16 square cm
Step-by-step explanation:
Area of shaded region = Area of circle - Area of rectangle
[tex] = \pi {r}^{2} - lw \\ = 3.14 \times ({12)}^{2} - 10 \times 3 \\ = 3.14 \times 144 - 30 \\ = 452.16 - 30 \\ = 422.16 \: {cm}^{2} [/tex]