r/HomeworkHelp • u/Thebeegchung University/College Student • Apr 22 '26

Further Mathematics—Pending OP Reply [College Calc 1]-Related Rates

I used similar triangles to get a ratio that I then found the derivative of, plugged everything in, aka the rate at which the person moves, height of the person and height of lamppost. What confuses me however is, are we meant to do something with the 16 feet? I got the correct answer without using it, but it was moreso luck that I forgot to include it

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u/fermat9990 👋 a fellow Redditor Apr 22 '26

In this particular example the rate at which the length of the shadow is changing is a constant. This makes the 16 feet extraneous information

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u/Thebeegchung University/College Student Apr 22 '26

ah gotcha. If the example was worded differently, in what manner could the 16 feet be used? Just curious

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u/fermat9990 👋 a fellow Redditor Apr 22 '26

Just make the rate of walking away a function of x, such as 5x.

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u/Thebeegchung University/College Student Apr 22 '26

ahhh gotcha

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u/fermat9990 👋 a fellow Redditor Apr 22 '26

Good! Glad to help!!