Please help, will fan and medal a man is 6ft tall walks at the rate of 5ft/sec toward a streetlight that is 16 ft above the ground. At what rate is the length of his shadow changing when he is 10 ft from the base of the light?

Question

welshfella · Answer

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welshfella · Answer

this is a probel about related rates,   right radar?

welshfella · Answer

use calculus I guess

radar · Answer

I thought it was, but still was  pondering......since he is walking toward the light source, I think the rate for the shadow is changing but I am confused to whether it is increasing or decreasing lol, getting too old for this .

welshfella · Answer

yea - i am confused about the same thing.!!
The distance between him and the lamp is decreasing as he walks wowards it and  will the shadow aaalso be decreasing?

welshfella · Answer

mahbe we ought to make ditance from lamp = to x

kayders1997 · Answer

Similar triangles the teacher told us

radar · Answer

I feel so foolish that I havent figured that out, I am studying your diagram and trying to visualize the shadow length change rate sign as he moves towards the light.

welshfella · Answer

hmm - shadow is X  so it will increase?

zepdrix · Answer

We were doing this problem in Twiddla, https://www.twiddla.com/2548723 sorry for being sneaky, didn't know people were still looking at it >.<

welshfella · Answer

I'm tired - thats my excuse!!

kayders1997 · Answer

Lol its okay we figured it out, but thanks for the help from everyone else :)

welshfella · Answer

ah yes similar triangles and  rate will be -5