选择题
2013 AMC 8 Problem 23: Semicircles on Triangle Sides
Angle ABC of triangle ABC is a right angle. The sides of triangle ABC are the diameters of semicircles as shown. The area of the semicircle on AB equals 8π, and the arc of the semicircle on AC has length 8.5π. What is the radius of the semicircle on BC?
2013 AMC 8 第23题：三角形边上的半圆
三角形ABC的角ABC是直角。三角形ABC的边是半圆的直径，如图所示。 AB 上的半圆面积等于 8π，AC 上的半圆弧长为 8.5π。 BC上半圆的半径是多少
A.
7
B.
7.5
C.
8
D.
8.5
E.
9