英语翻译英语数学题帮翻译下Angle ABC of △ABC is a right angle.The sides of

Angle ABC of △ABC is a right angle.
角ABC是△ABC中的直角.
The sides of △ABC are the diameters of semicircle as shown.
△ABC的边是半圆的直径,如图所示.
The area of the semicircle on BC equals 8pi,and the arc of the semicircle on AC has length 8.5pi.
BC上的半圆面积等于8pi, AC上的半圆弧长为8.5pi.
What is the radius of the semicircle on BC?
在BC上的半圆的半径是多少?

ΔABC的∠ABC是直角。ΔABC的边是半圆的直径。以BC为直径的半圆面积为8π，以AC为直径的半圆弧长为8.5π，问以BC为直径的半圆的半径是多少？