Tolong pakai caraaaaaaaaAa

L persegi = s x s = 18 x 18 = 324
L ∆ = 1/2 x a x t = 1/2 x 12 x 17 = 102
L persegi panjang = p x l = 12 x 1 = 12

L = 324 + 102 + 12
L = 438