请教GWD -2-6数学题思路

Radia_ting

GWD 2-6

The figure above shows the dimensions of a semicircular cross section of a one-way tunnel.  The single traffic lane is 12 feet wide and is equidistant from the sides of the tunnel.  If vehicles must clear the top of the tunnel by at least ½ foot when they are inside the traffic lane, what should be the limit on the height of vehicles that are allowed to use the tunnel?

A.     5½ ft

B.     7½ ft

C.     8 ½ ft

D.     9½ ft

E.      10 ft

此题有一幅图，就是一个半圆，什么也没有。我当时做的时候没思路，但猜估计是A和B中的某个答案。

请高人指点迷津啊！

jessicafairy

想说直径是12ft,车辆再升高0.5ft就要碰到顶了吗？

这样的话也太简单了就是6-0.5=5.5

题目的关键就是题目的意思了。。。。

Radia_ting

many  thanks !!

新鲜的跳蚤

ding!!!!!!!!