Answer:
72 ft²
Step-by-step explanation:
Calculate the area of each face and then sum them.
area of base = 4 × 5 = 20 ft²
area of back = 5 × 3 = 15 ft²
area of sloping face = 5 × 5 = 25 ft²
area of 2 triangular faces = 2 × 
× 4 × 3 = 4 × 3 = 12 ft²
Thus
surface area = 20 + 15 + 25 + 12 = 72 ft²
Height of the trapezoids = sqrt (17^2 - 8^2) = 15cms
base = 19 cms
(b) area of each trapezoid = 15/2 (35 + 19) = 405 cm^2
Total area painted blue = 2*405 = 810 cm^2
(c) length of the edges of one trapezoid = 35 + 19 + 2(17) = 88 cms
So one piece of sandpaper ( can sand up to 80 cm) will not be enough to sand all of the edges.
Volume =
multiply r by 2 and you will get diameter
