Question

The cross-section of a canal is a trapezium in shape. If the canal is 10m wide at the top, 6m wide at the bottom and the area of cross-section is 72 sq.m, determine its depth.

Answer 1

The cross-section of the canal is a trapezium

Area of a Trapezium = `(1)/(2)("a" + "b") xx "h"`,

Where a and b are the lengths of its parallel sides
Let h the perpendicular distance between them
here, a = 10, b = 6 and perpendicular distance = h
∴ Area of Trapezium

= `(1)/(2)(10 + 6) xx "h"`
= 72m²
⇒ 8h = 72
⇒ h = 9m.