Final answer:
The area of an ellipse with a major axis of 10 cm and a minor axis of 20 cm is 157 cm², calculated using the formula A = πab.
Step-by-step explanation:
To find the area of an ellipse with a major axis 2a = 10 cm and a minor axis 2b = 20 cm, you can use the formula A = πab, where a and b are the semi-major and semi-minor axes, respectively. In this case, a = 5 cm and b = 10 cm. Thus:
A = π(5 cm)(10 cm)
Calculating this gives:
A = π(50 cm²) = 157 cm² (to three significant figures, because π is approximately 3.14).
Therefore, the area of the ellipse is 157 cm², which corresponds to option b).