Saturday, December 12, 2009

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

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

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.

2 comments:

someone else said...

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30 degrees is the angle between the x-axis and the vector

vect said...

ever the angle of the vector and the x-axis and not

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