The figure is composed of 2 figures.
rectangular prism + pyramid
Find the surface area of each figure, and then add.
Surface area rectangular prism: 2base area +4 lateral area
Length: 10
width : 10
heigth : 5.6
Since the top of the rectangular prism is not part of the surface area, we only use one base.
Surface area = (length x width) + 4 (Length x height )
SA1 = (10x10) + 4 (10x5.6) = 100 + 224 = 324 in2
Surface area of a pyramid = base area + 1/2 p s
p= perimeter of the base = 10+10+10+10 =40
S = slant = 11
base area = 10x10= 100 ( not used )
SA2 = (1/2 x 40 x 11 ) = 220
Add both = 220 + 324 = 544 in2