Bob need to paint 205 square feet.
Solution:
Length of the door = 7 ft
Breadth of the door = 5 ft
Area of the door = length × breadth
= 7 × 5
= 35
Area of the door = 35 ft²
The given image is a trapezoid.
Top base = 12 ft
Bottom base = 20 ft
Area of the trapezoid = [tex]\frac{1}{2} \times\text{sum of the parallel sides}\times\text{height}[/tex]
[tex]$=\frac{1}{2}\times(12+20)}\times15[/tex]
[tex]$=\frac{1}{2}\times 32\times15[/tex]
= 240
Area of the trapezoid = 240 ft²
Surface area to paint = Area of the trapezoid – Area of the door
= 240 ft² – 35 ft²
= 205 ft²
Hence Bob need to paint 205 square feet.
