Multiplication of vector problem

AI Thread Summary
The problem involves finding the magnitude of vector A given that A*B equals 30.0 m² and B equals 5.00 m at 60 degrees. The discussion suggests using the dot product formula, indicating that A's components should be calculated based on its angle relative to B. One participant attempted to use a right triangle approach but expressed uncertainty about the next steps. It is recommended to set up simultaneous equations to solve for the unknown angle and magnitude of vector A.
Adrianw2
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Homework Statement


Let B = 5.00m at 60 degrees. Let C have the same magnitude as A and a direction angle greater than that of A by 25.0 degrees. Let A*B = 30.0 m^2 and B*C = 35.0 m2. Find A.


Homework Equations


Pythagoras maybe.


The Attempt at a Solution


Well, if A*B is 30 m^2, and B is 5.00m, then shouldn't A = 6.0 m? However, I don't think it's that easy, so I made the right angle triangle with B (5.0m) as the hypotenuse at 6 meters above the horizontal, and got 4.33m as the opposite and 2.5m as the adjacent. Am I going to be calculating areas of triangles? I'm not really sure where to go from there.

Thanks
 
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I'm assuming the astericks denote the scalar product? I think your going to have to set up a system of simulatenous equations.
 
Yeah, the astericks are actually a dot, so it may have something to do with the dot product where it's AxBx + AyBy or something along those lines.
 
Adrianw2 said:
Yeah, the astericks are actually a dot, so it may have something to do with the dot product where it's AxBx + AyBy or something along those lines.
I suggest you write out two equations using \theta to denote the unknown angle.
 
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