Home > categories > Mechanical Parts & Fabrication Services > Needle Bearings > help on this math question about bearings?
Question:

help on this math question about bearings?

a boat sails on a bearing of N15E for 10 km then on a bearing of S85E until it is due east of starting point the distance from the starting point to the nearest km is thena. 10 kmb 38c. 110d. 113e.114

Answer:

Sketch the situation and you have a triangle ABC, where A is the starting point, B is the turn after 10km, and C is the ending points. From the bearings, angle A is 75° (90° - 15°), angle B is 100° (85° + 15°), and so C must be 5°. Side c (opposite from C) is 10 km. Solve for side b (opposite from B) using the law of sines: b / (sin B) = c / (sin C) b = c * (sin B)/(sin C) = (10 km) * (sin 100°) / (sin 5°) Now, put your calculator in degree mode and see if the answer is closer to 113 or 114.
My answer is a. I plotted the bearings on a plane: starting point is (0,0) and got (15,10), and (85,0). This means the first distance traveled by the boat was the nearest distance to the starting point.

Share to: