Answer:
Given,
There is a feeding trough shaped like a rectangular right face ( opened from the top face ),
Having length, l = 6 m,
Width, w = 4 m,
And, height, h = 5 m,
(a) Since, each face is rectangular shape,
Thus, the area of front face or back face = l × h = 6 × 5 = 30 m²,
Area of bottom face = l × w = 6 × 4 = 24 m²,
Area of either of side face ( left face or right face ) = w × h = 4 × 5 = 20 m²,
(b) We know that the surface area of a rectangular prism is,
A = 2(lw + wh + hl)
= 2 (24+20+30)
= 2(74)
= 148 m²
Since, feeding trough is open from the top,
So, its surface area would be get after subtracting top face area from total surface area of the prism,
Also, the area of open face = l × w = 6 × 4 = 24 m²
Hence, the total surface area of the feeding trough = 148 - 24 = 124 m²
