Find the cross-sectional area of a gutter

[LordofDirT]

"A rain gutter is to be constructed from a metal sheet of width 30 cm by bending up one-third of the sheet on each side through an angle (theta)

Show that the cross-sectional area of the gutter is modeled by the function A(theta)=100sin(theta)+100sin(theta)cos(theta)"

My Question:

what is meant by cross-sectional?

 

[mgb_phys]

It's simply the area if cut across it.
So if you bent up the two sides by 90deg it would be a a square 10cm wide by 10cm high = csa of 100cm^2

 

[LordofDirT]

what does "csa" mean?

 

[mgb_phys]

Cross Sectional Area

 

[LordofDirT]

...Are the cross-sections where I bend the metal frame, so that each of my cross-sections will have a width of 10cm.?

EDIT: nm, your previous post clarified.