<u>Given</u>:
The radius of the circle is 10 cm
The central angle of the circle is (360 - 90)° = 270°
We need to determine the area of the composite figure.
<u>Area of the composite figure:</u>
The area of the figure can be determined using the area of the sector formula.
Thus, we have;
Substituting and in the above formula, we get;
Simplifying, we get;
Multiplying, we get;
Dividing the terms, we get;
Thus, the area of the composite figure is 235.5 cm²
Hence, Option C is the correct answer.