Rusuk balok yang bertemu pada sebuah pojok balok berbanding 4:4:1. Volume balok 432 liter. Berapakah luas permukaan balok?
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Misal: p = 4X, l = 4X, t = X V = 432 plt = 432 4X x 4X x X = 432 16X^3 = 432 X^3 = 27 X = 3√27 X = 3 p = 4•3 = 12, l = 4•3 = 12, t = 3 L = 2 ( pl + pt + lt) = 2 ( 12•12 + 12•3 + 12•3 ) = 2 ( 144 + 36 + 36 ) = 2 (216) = 432 cm^2
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