GMAT Quantitative Reasoning Practice Test 6

Because you know that the triangle is equilateral from statement (1), you also know that each side has the same measure and that each angle is 60 degrees. This does not, however, tell you the length of the diameter or radius of the circle,
which you need to know in order to find the area. Statement (2) alone is also insufficient because it tells you the length of one side of the triangle, but no other information about the figure. Using both statements together, the diameter is then
16; thus, the radius is 8. Therefore, the area of the semicircle can be calculated.