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April 22nd, 2009, 07:38 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, 01:26 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, 02:16 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 rightangled triangle, if one angle is 57 degrees and the side opposite is 12 km. 
October 16th, 2009, 03:07 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 180147 = 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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