Keliling suatu persegi panjang 66 cm. jika perbandingan panjang dan lebar 7 : 4 . maka luas persegi panjang tersebut adalah?
dnnyz07
Kell = 66 cm P : L = 7 : 4 misal sebenarnya 7b : 4b Luas = p x l = 7b x 4b = 28b² (ini rumusnya) maka kell = 66 cm 2(p + l) = 66 2(7b + 4b) = 66 2(11b) = 66 22b = 66 b = 66/22 b = 3
L = 28b² = 28 x 3² = 28 x 9 = 252 cm²
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FinandaAzzahra
K = 2 (p + l) 66 = 2 (p + l) p + l = 66 : 2 p + l = 33
p = 7/(7 + 4) × 33 p = 7/11 × 33 p = 21 cm l = 4/(7 + 4) × 33 l = 4/11 × 33 l = 12 cm
P : L = 7 : 4
misal sebenarnya 7b : 4b
Luas = p x l
= 7b x 4b
= 28b² (ini rumusnya)
maka
kell = 66 cm
2(p + l) = 66
2(7b + 4b) = 66
2(11b) = 66
22b = 66
b = 66/22
b = 3
L = 28b²
= 28 x 3²
= 28 x 9
= 252 cm²
66 = 2 (p + l)
p + l = 66 : 2
p + l = 33
p = 7/(7 + 4) × 33
p = 7/11 × 33
p = 21 cm
l = 4/(7 + 4) × 33
l = 4/11 × 33
l = 12 cm
L = p × l
L = 21 × 12
L = 252 cm²