GRE考试

【单选题】In the figure at the right, the legs of fight triangleAC
B、are diameters of the two semicircles. IfA
B、= 4, what is the sum of the areas of the semicircles


A、π
B、2π
C、4πD、8π
E、16π

网考网参考答案：B
网考网解析：
Let x and y be the radii of the two semicircles. Then the legs of right triangle ACB fire 2x and 2v, and by the Pythagorean theorem (2-x) 2 + (2y) 2 = 4 2 . Then 4x 2 + 4y 2 = 16, and x 2 + y 2 = 4. Since the area of a semicircle of radius r is , the sum of the areas of the semicircles is **Use TACTIC 2, Chapter 11. Pick numbers a and b for the legs of the triangle. For exam- ple, if a is 2, then by the Pythagorean theorem 2 2 + b 2 = 4 2 . document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>