Answer:
262 square feet
Step-by-step explanation:
The lateral surface is the side surfaces, except top and bottom.
There are 3 lateral surfaces.
The 2 sides are triangles with length 20 and height 8.5
And
The back is a rectangle with length 12 and height 8.5
We sum up all the 3 surface areas, that will give us the answer.
Area of triangle is (0.5) * length * height
So,
Area of 1 triangle = 0.5 * 20 * 8.5 = 80
Area of 2 triangles = 80 * 2 = 160
Area of rectangle = length * height
so,
Area of back rectangle = 12 * 8.5 = 102
Total Lateral Surface Area = 160 + 102 = 262 square feet
