tolong yaa kak..........

Kesebangunan

28.
Δ PQS  kongruen  ΔPRT
karena :
PQ = PR
<P = < P
PS = PT

29.
ΔABD kongruenΔ EBD, sebab
<A = < E
BD = BD
<ABD = <EBD
maka
AB = BE

30.
Δ AEC sebangun Δ ADB
<A = < A
<E = < D
< C = < B
AC/EC = AB/DB
20/12 = 12/DB
DB = 12 x 12 / 20
DB =  144/20
DB = 7, 2