Calculating Width of Metal Sheet for Corrugated Roofing Panels

[hisotaso]

Homework Statement

"A manufacturer of corrugated metal wants to produce metal roofing panels that are 28 in. wide and 2 in. thick by processing flat metal sheets."

the illustration shows that by "2 in. thick" they are referring to the distance between the crest and valley of the sine wave.
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"Verify that the equation of the sine wave is y=sin[(pi*x)/7]"

This is the part that has me confused.
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"Find the width w of a flat metal sheet needed to make a 28-inch panel."

Here they are just asking "Find the arc length of the sine wave from x=0 to x=28" yes?

Homework Equations

y=sin[(pi*x)/7]

The Attempt at a Solution

I haven't started the problem yet, my question is how would I verify the equation of the sine wave?

 

[Klockan3]

You lack one fact in the qiuestion, and its either the amount of periods you want on the whole panel or the width between two periods.

As evident of that equation you get 1 period per 14 inches or 2 periods total over the whole panel.

 

[hisotaso]

I figured it out, I hadn't noticed that the picture provided shows that the processed metal sheet completes 2 periods over the distance of 28 inches.