YAMT: help with calculus

alphatarget1

Diamond Member
Dec 9, 2001
5,710
0
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sorry i've been posting here so often :p i need to finish this stuff ASAP but i got stuck on the last problem :( I just need some pointers.

a lighthouse is located on a small island 3 km away from the nearest point P on a straight shoreline and its light makes four rev/min. how fast is the beam of light moving along the shoreline when it's 1 km from P?

ok this is a triangle problem. x= pheta (can't type that) i got tan (x)=3/y and i'm trying to get d(y)
d(x) would be 4(2pie)/min=8 pie/min

the change in the angle would affect the speed along the shoreline (y) but do i just put d(x)/d(y) and solve it?
 

notfred

Lifer
Feb 12, 2001
38,241
4
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This is my dad's absolute favorite math problem. He's probably got the solution memorized.