
Mark M. answered 08/09/15
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Mathematics Teacher - NCLB Highly Qualified
Draw and label a diagram.
Label the starting point "A."
Draw a line to the right ending at "B."
A true bearing is measured clockwise from North (the positive y axis)
An angle of 235° terminates 55° to the left of the negative y axis.
Draw a line from B to a point directly below A. Label this C.
∠ABC = 35°
cos 35° = 400 / BC
0.819152044 ≈ 400 / BC
0.819152044 BC ≈ 400
BC ≈ 488.090328
The boat must travel approximately 488 miles to be directly south of the starting point.