问GWD2 Q6 and Q30

Q6 

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

为什么答案是B？

Q30

In the figure, each side of square ABCD has length 1, the length of line segment CE is 1, and the length of line segment BE is equal to the length of line segment DE.  What is the area of the triangular region BCE?

A.     1/3

B.     (Ö2)/4

C.     1/2

D.     (Ö2)/2

E.      3/4

图形不会贴，请参考原题，两道都是图形题