Perbandinga panjang dan lebar persegi panjang 8:5 jika keliling 78 maka luas

P = 8x
l = 5x

K = 2 (p+l)
39 = 8x+5x
39 = 13x
x = 3

P = 24 cm
l = 15 cm

L = 24 × 15 = 360 cm²

k. persegi pjg = 78
2 (p+l) = 78
2 (8x+5x) = 78
2 (13x) = 78
26x = 78
x = 78/26
x = 3

p = 8x
p = 8.3
pjg = 24 cm

l = 5x
l = 5.3
lebar = 15 cm

Luas prsgi pjg = pjg x lebar
24 cm x 15 cm
360 cm pangkat 2

Jadi, luas persegi panjang 360 cm2