As shown in the figure, in the sector OAB with a radius of 1.0 and a central angle of 90.0, OA and OB are the diameters respectively as a semicircle, and the area of the shaded part in the figure is ()
Choices:
A:πcm²
B:\frac{2}{3}πcm²
C:\frac{1}{2}cm²
D:\frac{2}{3}cm²
Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
Question: As shown in the figure, in the sector OAB with a radius of 1.0 and a central angle of 90.0, OA and OB are the diameters respectively as a semicircle, and the area of the shaded part in the figure is ()
Choices:
A:πcm²
B:\frac{2}{3}πcm²
C:\frac{1}{2}cm²
D:\frac{2}{3}cm²
Please first conduct reasoning, and then answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
Question: As shown in the figure, in the sector OAB with a radius of 1.0 and a central angle of 90.0, OA and OB are the diameters respectively as a semicircle, and the area of the shaded part in the figure is ()
Choices:
A:πcm²
B:\frac{2}{3}πcm²
C:\frac{1}{2}cm²
D:\frac{2}{3}cm²