Billy is hiking in Colorado. He walks eastward four miles, then turns \(60\) degrees northward and walks six miles. How far is he from his starting point? Express your answer in simplest radical form.
You can use the cosine law
d^2 = 4^2 + 6^2 - 2 (4)(6) cos 120 (120 degrees is the angle between the two hiking segments)
d^2 = 76
d= sqrt 76 =8.72 miles from start