For this question, a straight line is the closest, and will always be.
To find the length of the line AC, we can see that it is the hypotnuse of a right triangle with the height of 8 and a base of ( using the pythagorean theorem) √261. Now, we square 8, 64, and the √261, 261, and find the sum.
64+261=325
The answer is square root of 325, and by taking 5 out, the final answer should be 5√13