Answer:
Increase in surface area = 126 cm²
Explanation:
Surface area of the rectangular prism has the dimensions as
Length = 42 cm
Width = 35 cm
Height = 64 cm
Total surface area of the rectangular prism = 2(lb + bh + hl)
Here, l = Length of the box
b = Width of rectangular box
h = height
Total surface area = 2(42×35 + 35×64 + 64×42)
= 2(1470 + 2240 + 2688)
= 12796 cm²
If height is increased by by 1.5 cm, new height of the box = 64 + 1.5 = 65.5 cm
Surface area of the box = 2(42×35 + 35×65.5 + 65.5×42)
= 2(1470 + 2240 + 2751)
= 12922 cm²
Increase in surface area = 12922 - 12796
= 126 cm²