First let's set up the problem

Let x be the distance from C to B. Then 14-x is the distance from C to D.

So the bird flies sqrt(5^2+x^2) to reach C, and then 14-x from C to D along the shoreline.

a) E = 1.1sqrt(25+x^2)+14-x

(dE)/(dx) = 1.1(2x)/(2sqrt(25+x^2))-x = (1.1x)/(sqrt(25+x^2))-1

At a critical point (dE)/(dx) = 0 so (1.1x)/(sqrt(25+x^2))-x =0

We need to solve for x.

`1.1x=sqrt(25+x^2)` , `1.21x^2=25+x^2`...

(The entire section contains 225 words.)

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