Question

The cross section of a canal is the shape of the canal is12m wide at the top of ,8m wide at the bottom $ the area of it cross section is 84 meter square,determine to depth

Answer 1

Hey there,

area of a trapezium =  1/2 (b + a) h
where  a and b are parallel sides and h is the altitude or distance between a and b.

In a canal, the floor of canal and the top water surface are parallel.  Height of trapezium is the depth of canal.

84 meters  =  1/2 ( 12 + 8) Height
Height = 168/20 = 8.4 meters

Hope this helps!