Question

Find the length of rectangular box whose area is 960metre and breadth

Answer 1

Step-by-step explanation:

length =l breadth =b height =h and l=2b

Area ⇒2lb+2bh+2hl=1200

⇒2×2b×b+2bh+2h×2b=1200

4b2+2bh+4bh=1200

6bh=1200−4b2

h=6b1200−4b2

d(v)=l×b×h=2b2×[6b1200−4b2]

d(v)=31200b−4b3

from volume to ve max, d′(v)=0

d(B)d(V)=31[1200−12b2]=0

1200=12b2b=10cm

l=2×b=20cm.h=6×101200