kak tolong kalo bisa cepat yaaaa.......

a) luas 18 x 9 : 2 = 81cm²
kel = 12 + 15 + 18 =45cm

b) 12 x 10 : 2 = 60cm²
kel = 13 +13 + 10 =36cm²

a.
L=1/2.a.t
=1/2.18.9
=81
K=12+15+18
=45

b.
L=1/2.a.t
=1/2.10.12
=60
K=13+13+10
=36