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My name is James. This is a secondary level question. I am a student. This question is about finding bearings. A boat race starts from point A, goes North to Point B, a distance of 1000 meters. The course is triangular. The bearing from point B to point C is South 70degrees West. The distance from Point B to point C is 1500 meters. Find the course bearing from C to A. I'm not sure which angle of the implied triangle to use for the I constructed a triangle with points A,B, and C. I tried to use the |
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Hi James, I drew a diagram of the triangle you described and added a North-South line at C. I agree that the bearing from C to A is S 71.2o E. There is a good explanation of bearings at a page kept by David Levesen, a faculty member in the Department of Geology at Brooklyn College, City Uiversity of New York.
There is however a problem with your solution. In your use of the Law of Sines you have 1500/sin(70). But the side of length 1500 m is not opposite the angle at B. First you should use the Law of Cosines to find the length of CA.
Once you know |CA| you can use the Law of Sines to find the angle at C.
Penny |
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