Finding the Hypotenuse with the Given Vector

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To find the hypotenuse given a vector, the sine law can be effectively used when two angles and one side (F1) are known. Initial attempts using cosine calculations were incorrect, leading to confusion about the hypotenuse (F2). Constructing a parallelogram can also aid in visualizing the problem and understanding the relationships between the forces. The discussion highlights the importance of recalling geometry principles, such as angle relationships. Ultimately, determining the components of the forces ensures equilibrium in the system.
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Here is the link to the problem http://imgur.com/MGcfdr7


I'm not really sure how to approach this. I initially thought you would get the resultant vector by doing 125cos(38) and that gave me 98, which I then divided by the cos(45) to get the hypotenuse, or F2, which gave me 138.6. It says that this isn't the right answer so I'm not sure what to do.
 
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Did you try to construct the parallelogram first?
 
sevag00 said:
Did you try to construct the parallelogram first?

No, how would I go about solving for F2 with that?
 
By using sine law. You have two angles and F1.
 
sevag00 said:
By using sine law. You have two angles and F1.

Sorry, is there anyway you could set this up for me? I don't really understand what you're saying.
 
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By using sine law you can easily get F2.
 
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sevag00 said:
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By using sine law you can easily get F2.

Oh awesome, thank you! Just got it after digging through my memories of old geometry classes. Forgot about the angles flipping and all that jazz. Thanks for everything
 
Here's another way which gives the same answer. Determine the components of the two forces in direction across the channel. They must be equal in magnitude and opposite in sign in order for the rear of the boat not to move in the cross channel direction.

Chet
 
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