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October 30, 2014

October 30, 2014

Posted by **Nikki** on Sunday, September 5, 2010 at 12:56pm.

I'm totally stumped by this question. So far I have the picture of the problem, and that's about it. Help please?!

Thank you

- Math -
**Reiny**, Sunday, September 5, 2010 at 2:56pmThis is a good Calculus question.

label your diagram as follows

A - position of boat

B - point on shore closest to A

C- point on shore where he should row to (our answer)

V - position of the village

Clearly ABC is a right angle,

let BC = x, then CV = 6-x

AB = 2

AC = √(x^2 + 4)

Time in water = √(x^2 + 4)/2

time along shore = (6-x)/5

Time = (1/2)(x^2 + 4)^(1/2) + 6/5 - x/5

dTime/dx = (1/4)(x^2+4)^(-1/2)(2x) - 1/5

set this equal to zero and solve for x

let me know what you got.

- Math -
**Anonymous**, Tuesday, July 1, 2014 at 1:13pm4/sqrt(21)? or 0.87287

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