Question

the surface area of cuboid is 1372 sq cm. if it's dimensions in ratio 4 : 2: 1 then what will be the length​

Answer 1

Answer:

lenght is 28 cm

explanation

Answer 2

Answer:

$surface \: area \: of \: cuboid \: = 2(lb + bh + hl)$

$here \:let \: length(l) = 4x \\ breadth(b) = 2x \\ height(h) = 1x \\surface \: area = 2(4x \times 2x + \\ 2x \times x + 4x \times x) \\ = 2(8x ^{2} + 2x ^{2} + \\ 4x ^{2} ) \\ = 28x ^{2}$

$but \: surface \: area = 1372cm ^{2} (given)$

$therefore \: according \: to \: question \\ 28x ^{2} = 1372 \\ => x^{2} = 49 \\ =>x = \sqrt{49} \\ x = 7cm$

$hence \: length = 4x = 4 \times 7 = 28cm$