Question

The cross-section of a canal is in the shape of a trapezium. If the canal is $12$ m wide at the top and $8$ m wide et the bottom and the area of its cross-section is 84 $m^2$, determine its depth.

• A. $8.4$ m
• B. $7.4$ m
• C. $4.8$ m
• D. $6.4$ m

Answer 1

The correct option is A $8.4$ m

Given :- $a=12m$ , $b=8m$ , height $=h$ and area of trapezium =$84m^2$
So, putting the respective values , we get,
Area of trapezium = $\frac{1}{2}\times (a+b)\times h$
$84=\frac{1}{2}\times (8+12)\times h$

$84=\frac{20h}{2}$

$84=10h$

$h=\frac{84}{10}$
$h=8.4m$