Question

the sum of lenght , breadth , and height of a cuboidvis 19 cm and diagonal is equal to 11 cm find the surface area

Answer 1

l+b+h=19
squaring both side
(l+b+h)²=19²
by using (a+b+c)²
l²+b²+h²+2(lb+bh+hl)=361------eq1
Diagonal of cuboid,
⇒√l²+b²+h²=11
⇒l²+b²+h²=11²
⇒l²+b²+h²=121
now,putting the value in equation 1
⇒l²+b²+h²+2(lb+bh+hl)=361
⇒121+2(lb+bh+hl)=361
⇒2(lb+bh+hl)=361-121
⇒2(lb+bh+hl)=240 answer
  
   so the surface area of cuboid is 240.