tolong kak 18 - 20 pakai cara kak

18.
Luas Persegi panjang = 16
AB x BC = 16
AD x DC = 16

Luas segitiga ADC = 1/2 x AD x DC = 1/2 x 16 = 8 m²

BE = 1/2 AB
BF = 1/2 BC

Segitiga BEF
= 1/2 x BE x BF
= 1/2 x 1/2 AB x 1/2 BC
= 1/8 x AB x BC
= 1/8 x 16
= 2 m²
 
 Luas  trapesium AEFC = 16 - 8 - 2 = 6 m²

19.
Luas jajaran jenjang = 20 x 9 = 180 cm²

Jajaran jenjang diputar
DF = 180 / 10 = 18 cm

20.
Keliling = 2 x (16 + 9) = 50 cm