Step-by-step explanation:
(i) Area of the first cross section
base,b = 8 m, height,h = 10 m
Area of the triangle = [tex]\frac{1}{2}[/tex] bh
area = [tex]\frac{1}{2}[/tex] (8) (10)
area = 40 m²
(ii) Area of the second cross section
base,b = 12 m, height,h = 10 m
Area of the triangle = [tex]\frac{1}{2}[/tex] bh
area = [tex]\frac{1}{2}[/tex] (12) (10)
area = 60 m²
Difference in the areas of the cross sections = 60 - 40 = 20 m²