Question

Keliling suatu persegi panjang 42cm.jika panjang:lebar =4 :3, tentukan luasnya

Answer 1

keliling = 2(p+l)
42 = 2(4y + 3y)
42 = 2(7y)
42 = 14y
y = 42 : 14
y = 3

p = 4y = 4(3) = 12 cm
l = 3y = 3(3) = 9 cm

luas = p x l
luas = 12 cm x 9 cm
luas = 108 cm²

Answer 2

2(p+l) = 42 
p+l = 42/2
p+l = 21
setelah itu kita gunakan perbandingan
p : l = 4 : 3
panjang = 4 /(4+3) x 21 = 4/7 x 21 =12
lebar= 3/7 x 21 = 9
jadi luasnya = p . l = 12 . 9 = 108 cm^2