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Jawaban:
Bangun Datar
Persegi panjang
Segitiga
Penjelasan dengan langkah-langkah:
1. Keliling persegi panjang = 60 cm
2 ( p + l ) = 60
( p + l ) = 60/2
( p + l ) = 30 cm
p = 30 – l
Luas = P x L
(30-l)xl = 0
30l-l²=0
-l²+30l=0
-2l+30=0
-2l=-30
l=-30/-2
l=15 cm
P=30-l
=30-15
=15 cm
P = 15 cm dan L = 15 cm
Luas maksimum = 15 cm x 15 cm = 225 cm²
2. S₁+S₂=50 cm
S₁=50-S₂
Luas segitiga
1/2 x a x t
1/2 x S₁ x S₂
1/2 x (50-S₂) x S₂
1/2 x (50S₂ – S₂²)
25S₂-1/2S₂²
-1/2S₂²+25S₂=0
2(-1/2)S₂+25=0
-1S₂+25=0
-S₂+25=0
-S₂=-25
S₂=-25/-1
S₂=25 cm
S₁=50-S₂
=50-25
=25 cm
S₁=25 cm dan S₂=25 cm
Luas maksimum = 1/2 x 25 x 25 = 1/2 x 625 = 312,5 cm²
Demikian
Semoga membantu dan bermanfaat!