$19 \cdot 7$ If the perimeter of an equilateral triangle and a regular hexagon are equal, and the area of the triangle is 2, then the area of the hexagon is
(A) 2 .
(B) 3 .
(C) 4 .
(D) 6 .
(E) 12 .
(21st American High School Mathematics Examination, 1970)
［Solution］From the figure, it is easy to see that
$S_{\text {hexagon }}: S_{\triangle}=6: 4=3: 2$. Given $S_{\triangle}=2$, then $S_{\text {hexagon }}=3$. Therefore, the answer is $(B)$.