9514 1404 393
Answer:
A. 53.5cm^2
Explanation:
The area of the circle is ...
A = πr²
A = 3.14(5 cm)² = 78.5 cm²
The area of the triangle is ...
A = 1/2bh
A = 1/2(10 cm)(5 cm) = 25 cm²
The shaded area is the difference between the circle area and the triangle area:
shaded = 78.5 cm² -25 cm² = 53.5 cm²
_____
Additional comment
As with many multiple-choice questions, you can simply pick the answer that is not outlandish. The circle will fit into a square that is 10 cm on a side, so its total area is less than 100 cm² (eliminates choice B).
The shaded area is definitely more than 1/4 of that 100 cm² square, so choices C and D are eliminated, too. The only choice that is not unreasonable is choice A.