SOLUTION: A man walks due west for 4 km he then change direction and walk on a bearing of 197° until he is southwest of his starting point how far is he then his starting point

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Question 1175814: A man walks due west for 4 km he then change direction and walk on a bearing of 197° until he is southwest of his starting point how far is he then his starting point

Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


A bearing of 197 degrees is 17 degrees west of south.

After walking 4 miles west from his starting point, his displacement in the x direction is 4 miles west and his displacement in the y direction is 0.

In walking a distance d at an angle 17 degrees west of south, his displacement in the x direction is d%2Asin%2817%29 (west), and his displacement in the y direction is d%2Acos%2817%29 (south).

So his total displacement is 4%2Bd%2Asin%2817%29 west and d%2Acos%2817%29 south.

He is southwest of his starting point when his displacements west and south are equal.

4%2Bd%2Asin%2817%29+=+d%2Acos%2817%29

That is not an equation you are going to solve manually; use a calculator.

Then remember that the question asks for how far he is from his starting point. The solution to the equation you solved is his displacement in each of the x and y directions; so his distance from his starting point is that displacement multiplied by the square root of 2.

(To check your calculations, note my answer was a bit over 8km....)