satu lagi plisbantu jawab

10)
keliling ∆ = Sisi 1 + Sisi 2 + Sisi 3
30 = (3x+1) + (2x+2) + (4x)
30 = 9x + 3
27 = 9x
3 = X

Sisi 1 = (3x+1)
= 3.3 +1
= 9 + 1
= 10 cm

Sisi 2 = (2x+2)
= 2.3 + 2
= 6 + 2
= 8cm

Sisi 3 = (4x)
= 4.3
= 12 cm

luas ∆ = alas × tinggi ÷ 2
luas ∆ = 8 × 10 ÷ 2
luas ∆ = 40cm²

tolong jadikan jawaban terbaik bila anda puas :)