1、16
2、DC = 6，sinB = 44141
3、D
4、B
5、C
6、12
7、设AB = a，则BC = asin30° = 12a，B′C′= atan30° = 33a，
∴ BC∶B′C′∶B″C″ = 12∶33∶1
8、∠A = 30°，∠D = 45°.
9、tanA = 34
10、B′C′= B″C = BC = ABcosB = 6，BC′= B′C′tan60° = 63，
∴ CC′= BC - BC′= 6 - 63 = 6 - 23.
11、作AF ⊥ OE，垂足为F，OF = 3cos55°，AD = OB + BE - OF ≈ 1.9（m）
12、FE = 20m，FC = BCtan30°，EC = BCtan60°，BCtan30° - BCtan60° = FE，BC ≈ 17.3（m）