-----|-----|-----|-----|----
D C A B
A-B-C-D
C ∈ AD
D ∈ CB
AB 2
---- =---
CB 3
CD 2
-----=---
DB 3
CB = 15 cm
------------------------------------l-----
CD , DB , AC , AD , AB = ?
----------------------------------l--l----
AB 2
----=--
15 3
15°2 30
AB = -------- = ----- = 10 cm ⇒ AB = 10cm
3 3
AC = AB - CB = 15 - 10 = 5 cm ⇒ AC = 5 cm
CD = DB - CB
DB = CD + CB