Math, asked by knishkabohraknishka, 1 year ago

if l,b,h,s and v are length,breath,height,surface area and volume respectively of a cuboid prove that 1/v=2/s(1/l+1/b+1/h)

Answers

Answered by mysticd
9
here s = 2 (lb+lh+bh)
s/2 = (lb+lh+bh )---(1)

1/l +1/b +1/h =  [ bh+lh+lb]/lbh  =(s/2) /lbh = ---(2)

RHS = 2/s * [ 1/l +1/b+1/h]

= 2/s * [(s/2)/lbh]     { ∵ (2)}
= 1/ (lbh)
= 1/v     [ ∵ volume =v = lbh]
= lhs

knishkabohraknishka: 1/l +1/b +1/h = [ bh+lh+lb]/lbh =(s/2) /lbh = ---(2) cannot understand this line
mysticd: lcm of l, b, h = lbh
knishkabohraknishka: ok thnx
mysticd: do u understand
knishkabohraknishka: yes
mysticd: :)
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