J
James Harwood
Guest
A boat sails at a speed of 11 knots due east. The current flows on a bearing of 210° at a speed of 6 knots. Find the resultant speed of the boat.
With the diagram one would use the cosine rule to work this out, so that's quite simple . .
http://i166.photobucket.com/albums/u94/joshmohoboob/mechanics.jpg
That's my diagram, but for some reason the book uses cos30 instead of cos60 like I would have. WHY?!?!?!?!
Please provide a solution - and an explanation (preferably with a description of a diagram or drawing one) that can explain to me why you use cos30 instead of cos60.
BEST ANSWER GETS 5 STARS.
The solution is 6.533 knots.
With the diagram one would use the cosine rule to work this out, so that's quite simple . .
http://i166.photobucket.com/albums/u94/joshmohoboob/mechanics.jpg
That's my diagram, but for some reason the book uses cos30 instead of cos60 like I would have. WHY?!?!?!?!
Please provide a solution - and an explanation (preferably with a description of a diagram or drawing one) that can explain to me why you use cos30 instead of cos60.
BEST ANSWER GETS 5 STARS.
The solution is 6.533 knots.