[w + (h/tan θ)] × h
<h3>Further explanation</h3>
We aim is to find the area of the trapezoidal cross-section of the irrigation canal.
The formula for the area of the trapezoid is 
- a & b = parallel sides
- h = height
We assume the lower side is
and the upper side is b = x + w + x or
. See the attached picture.
In the right triangles located on the left and right of the trapezoid, we calculate the value of x based on trigonometric ratios namely tan of theta.



Substitute the equation of x to 
We get 
Finally all components are complete and can be substituted into a formula to calculate the area of a trapezoid.




Hence, the area of the trapezoidal cross-section of the irrigation canal is 
<h3>Learn more</h3>
- Find out the area of parallelogram brainly.com/question/4459688
- The order of rotational symmetry of rhombus brainly.com/question/4228574
- Find out the coordinates of the image of a point after the triangle is rotated 270° about the origin brainly.com/question/7437053
Keywords: the trapezoidal, cross-section of the irrigation canal, the area, the answer will be in terms of h, w, and θ, trigonometric ratios, tan, opposite, adjacent, height, sides