Thursday, December 17, 2009

Sail Boat Sails Diagram No Solution Required. Why Does The Book Use Cos30 And Not Cos60?

No solution required. Why does the book use cos30 and not cos60? - sail boat sails diagram

A boat travels at a speed of 11 knots to the east. The current flows in a direction of 210 ° at a speed of 5 knots. What is the resultant velocity of the boat.

http://i166.photobucket.com/albums/u94/j ...

That is my plan (click) is the link, but for some reason, the book uses cos30 instead cos60. Why is this so? I assume the North is 0 degrees, and horizontal angle of 60 degrees, not 30 Therefore, the construction of a diagram, as shown.

Then use the cosine law to solve. The answer is: 7.123 knots.

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