64

设
 B2C1/C1A1 = r
 A2C1/C1B1 = s
 
则
 A2A3/A1A2 = B2C1/C1A1 = r
 B2B3/B1B2 = A2C1/C1B1 = s
 A3A4/A2A3 = B2B3/B1B2 = s
 B3B4/B2B3 = A2A3/A1A2 = r
 A4A5/A3A4 = B3B4/B2B3 = r
 B4B5/B3B4 = A3A4/A2A3 = s
 A5A6/A4A5 = B4B5/B3B4 = s
 B5B6/B4B5 = A4A5/A3A4 = r

于是
 S_A1C1A2 = 4
 S_A2C2A3 = S_A1C1A2 * (A2A3/A1A2)^2 = 4 * r^2
 S_A3C3A4 = S_A2C2A3 * (A3A4/A2A3)^2  = 4 * r^2 * s^2
 S_A4C4A5 = S_A3C3A4 * (A4A5/A3A4)^2 = 4 * r^2 * s^2 * r^2
 S_A5C5A6 = S_A4C4A5 * (A5A6/A4A5)^2 = 4 * r^2 * s^2 * r^2 * s^2

又
 3 = S_B1C1B2 = S_A1C1A2 * B1C1/C1A2 * B2C1/C1A2 = 4 * 1/s * r
因此
  s = 4/3*r

可得
 24 = S_A4C4A5 =  4 * r^2 * s^2 * r^2 = 4 * (4/3)^2 * r^6
 9*6 = 16 * r^6
 r^2 = 3/2
 s^2 = (4/3)^2*r^2 = 16/9 * 3/2 = 8/3
 
 S_A5C5A6 = 4 * r^4 * s^4 = 4 * (3/2)^2 * (8/3)^2 = 4 * 4^2 = 64