1. **Problem a:** Find the area of a circle with radius 6.8 cm. 2. The formula for the area of a circle is: $$A = \pi r^2$$ where $r$ is the radius. 3. Substitute $r = 6.8$ cm: $$A = \pi (6.8)^2$$ 4. Calculate the square: $$6.8^2 = 46.24$$ 5. So, $$A = \pi \times 46.24$$ 6. Using $\pi \approx 3.1416$: $$A \approx 3.1416 \times 46.24 = 145.31$$ 7. **Final answer:** The area of the circle is approximately **145.31 cm^2**.