tolong bantu ka no 32

Cari panjang DE

AB/DE = BC/EC

AB/DE = (BE + EC)/ EC

18/DE = (20+ 10)/10

18/DE = 30/10

30 DE = 180

DE = 180/30

DE = 6

Luas DEC = 1/2 a. t

= 1/2. 10. 6

= 30 cm2 (C)