Question

The sum of l+b+h is 19cm and length of diagonal is 11cm.Find the expenditure to paint all tje surface of cuboid at Rs 9 per msquare

Answer 1

HELLO DEAR,



GIVEN THAT, :-

$d = \sqrt{ {l}^{2} + {b}^{2} + {h}^{2} } = 11 \\ = > 121 = {l}^{2} + {b}^{2} + {h}^{2} ..........(1) \\ \\ \\ \\ = > (l + b + h) = 19.......squaring \: both \: side \: \\ we \: get \\ = > {l}^{2} + {b}^{2} + {h}^{2} + 2(lb + bh + lh) = 361 \\ = > 121 + 2(lb + bh + lh) = 361 \: \: \: (using \: (1)..) \\ = > 2(lb + bh + lh) = 361 - 121 \\ = > 2(lb +bh + lh) = 240c {m}^{2}$
And the total cost =9×240=₹2160



I HOPE ITS HELP YOU DEAR,
THANKS