Question

A circular entrenchment, 54 m in diameter, is to be surrounded by a ditch 8 m wide at the top and 6 m wide at the bottom, and 5m deep. Find the volume to be excavated.

Answer 1

Answer:

Here your answer

The (Volume of frustum of radii 35 (27+8), 34 (27+1+6) and height 5) - (Volume of frustum of radii 27, 28 (27+1) and height 5),

= 6820

Hope it will help you

Answer 2

Answer:

6820 m³

Step-by-step explanation:

Since the ditch is 8 m wide at the top and 6 m wide at the bottom, the cross section of the ditch is a trapezium.

Parallel Sides of trapezium is 6m and 8m respectively.

h - perpendicular distance - 5m

Area = 1/2 (a + b) h = 1/2 (8+6) 5 = 1/2 x 14 x 5 = 35 sq. m

Volume = A . l

Volume = 35 x π D where D = 54 + 8 = 62

Volume = 35 x π x 62 = 6820 m³