tolong besertakan caranya

CD/EF = EF/AB
CD/16 = 16/20
CD/16 = 4/5
5 x CD = 4 x 16
5CD = 64
CD = 64/5
CD = 12,8 cm

*semoga membantu. sukses selalu ^_^

CD = EF / AB = CD / FE
16 / 20 = X / 16, kemudian dikali silang menjadi:
20X = 16.16
20X = 256
X = 256/20
X = 12,8