趣味的数学-121
三角形ABC中，∠C = 3∠A，a=27，c=48。求b的长度。
【AHSME】
对
35
9/sin (A) = b/sin (4A) = 48/sin (3A)
9*sin (3A) = 16* sin (A)
=> cos (A) = 5/6, sin (A) = 11^(1/2) / 6
b = 27/sin (A) * sin (4A) = 35
