Q.The sum of the length, breadth, and height of a rectangular box is 24 cm, and the length of its diagonal is 15 cm. What is the total surface area of the box?

Let the length, breadth, and height of the rectangular box be \(a\) cm, \(b\) cm, and \(c\) cm respectively. So, \[ a + b + c = 24 \quad \text{—— (i)} \] and \[ \sqrt{a^2 + b^2 + c^2} = 15 \quad \text{—— (ii)} \] Now, \[ (a + b + c)^2 = 24^2 = 576 \Rightarrow a^2 + b^2 + c^2 + 2(ab + bc + ca) = 576 \] From (ii), \[ a^2 + b^2 + c^2 = 15^2 = 225 \Rightarrow 225 + 2(ab + bc + ca) = 576 \Rightarrow 2(ab + bc + ca) = 576 - 225 = 351 \] ∴ The total surface area of the rectangular box is 351 square centimeters
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