The fourth and the third answer to the area of the shadow part of the figure

The fourth and the third answer to the area of the shadow part of the figure

Triangular?
5+5=10cm
10*10/2=50cm²
3.14*5²=78.5cm²
78.5/2=39.25cm²
50-39.25=10.75cm²
It must be right. I did