Answer:
15 cans
Explanation:
There are two shapes that make up the dog house, they are the triangular and rectangular prism, with the combination of a semi-circle and rectangle as the door opening.
The area of a rectangle for the top ( T ) and bottom ( B ) side view:
top height = 3ft, and width= 8ft
bottom height = 4.5ft, width= 8 ft
Area ( T ) = 3 X 8 = 24 ft^2
Area ( B ) = 4.5 X 8 = 36ft^2
The front and back view is a triangle and rectangle:
area of triangle = 1/2 x base x height
with the base = 4ft, and sides= 3 ft
height = sqrt( side^2 - (1/2 height)^2 )^0.5
= sqrt( 9 - 4 ) = 2.235
area of triangle( front and back ) = 1/2( 4 x 2.235 ) = 4.47 ft^2
area of rectangle ( back ) = 4 x 4.5 = 18ft
The entrance is a rectangle with area = 2.5 x 2 = 5ft^2
and semi-circle with area = (πr^2)/2 = (3.14 x 1^2)/2 = 1.57ft^2
area of entrance = 5 + 1.57 = 6.57ft^2
area of front view = 18 - 6.57 = 11.43ft^2
the total area of the doghouse is = 11.43 + 18 + 72 + 48 + 8.94 = 158.37ft^2
this is for just the outside. to get the total for inside and outside:
158.37 x 2 = 316.74ft^2
total area per paint can = 20ft^2
total number of cans needed = 316.74 / 20 = 15 paint cans