Pada gambar di samping AD=4cm BD=8cm. Luas ABC=

BD" = AD × DC
8" = 4 × DC
64 = 4 × DC
64/4 = DC
16 = DC

Luas = 1/2 × BD × AC
= 1/2 × BD × (AD + DC)
= 1/2 × 8 × 20
= 1/2 × 160
= 80

maaf kalau salah