Question

18

Answer 1

Answer:

a

Step-by-step explanation:

S.A for open-faced box= lb + 2(bh+lh)

= (7-2h)(7-2h) + 2[h(7-2h)+h(7-2h)]

= (7-2h)² + 2[2h(7-2h)]

= (7-2h)² + 4h(7-2h) in²