My Math Forum trigonometry bearings problem

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 April 22nd, 2009, 08:38 AM #1 Newbie   Joined: Apr 2009 Posts: 1 Thanks: 0 trigonometry bearings problem A helicopter pilot flies in the direction 147 degrees and lands when she is 12 km south of her starting point. How far did she fly? How do you solve this/approach this problem?
 April 22nd, 2009, 02:26 PM #2 Senior Member   Joined: Jul 2008 Posts: 895 Thanks: 0 Re: trigonometry bearings problem At 147 degrees, will [s]he not be NORTH of the starting point, albeit also westbound?
 April 22nd, 2009, 03:16 PM #3 Senior Member   Joined: Feb 2009 From: Adelaide, Australia Posts: 1,519 Thanks: 3 Re: trigonometry bearings problem Presumably it's 147 degrees true, i.e. clockwise from north. Draw a compass rose and conclude that 147 degrees true is equivalent to 57 degrees clockwise from east. So you must find the length of hypotenuse of a right-angled triangle, if one angle is 57 degrees and the side opposite is 12 km.
 October 16th, 2009, 04:07 PM #4 Newbie   Joined: Oct 2009 Posts: 1 Thanks: 0 Re: trigonometry bearings problem http://twitpic.com/lsl3r 1) find x. You do this by 180-147 = 33 degrees. (you just found one of the angles formed by the triangle) 2) Now that you know that angle, you can use trigonometry. In this case, its cos. 3) Cos = adjacent/hypotenuse = 12/y 4) Now you solve algebraically Cos (33) = 12/y y Cos 33 = 12 y = 12/Cos 33 y = 14.3 km

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