Question 1076356

Please help me find the length of the pond in the image linked below.
Pond: https://s2.postimg.org/gloq07w09/Math_Lake.png
<pre>Correct answer: {{{highlight_green(matrix(1,6, Length, "=", sqrt(480^2 + 565^2 - 2(480)(565) * cos (80^o)), "=", 674.8616, feet))}}}