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LanyaOsman
Nov 28, 2011, 08:25 AM
Need Help On these 2 questions I have a test tomorrow and I didn't catch the answers of these, is there anyone that know how to answer these?
1)The piolet of a single-engine airplane flies at a constant speed of 200 km/h at a bearing of N 25 degree E. There is a 40 km/h crosswind blowing southeast (S 45 degress E). What are the plane's actual speed and direction? Round the speed to the nearest tenth and the directiuon to the nearest degree.

2)To reach a campsite, a hiker first walks for 2 mi at a bearing N 40 degree E. Then He walks 3 mi due east. What are the magnitude and direction of his hike from his stating point to the campsite? Round the distance to the nearest tenth of a mile and the direction to the nearest degree.

Unknown008
Dec 1, 2011, 12:51 AM
1) Make sketches, they help A LOT.

First, draw a line, scale length 200 km/h at bearing 025, then where that line stops, draw another line, scale length 40 km/h and with bearing 225. The actual speed and direction is obtained by joining the two lines to get a triangle. The length of the last line you draw gives the speed of the plane and the angle with respect to the North gives the bearing.

You will have yo know your formulae though, namely the sine rule here:

\frac{\sin A}{a} = \frac{\sin B}{b}

The same principle applies to the second problem.