Even AA2, across BB 1 and d.

∫db 1∑a2 B2

∴D is the midpoint of AA2

∴C 1 is the center of gravity of △ABA2.

∴BC 1=2C 1D, or even C 1A2.

Yi Zheng c 1a 2∨AC

∴S 1=S/2

C2 is the center of gravity of △B 1BC.

∴C2B2=BB2/3

∴S2=S/3

A3C=BC/4

∴S3=S/4

∴S 1:S2:S3=6:4:3