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Homework Help: Vector Addition Question

  1. Jan 6, 2006 #1
    Man, my online physics course sucks. Every time there is a lab or an assignment, it's on stuff I haven't done, lol.

    Anyway I have an angle of 155 degrees separating one 18 N vector going 85 degrees northwest, and another vector going about 60 degrees southwest. The other angle is 12 N.

    I have to add them, somehow, and give the magnitude of the new vector and its angle.

    Then I take my new answer and use it to find the angle between it and another angle, which I already know. I should be able to do that easily enough with the protractor.

    I have only been taught to add vectors which create right trangles, any way to solve it with right triangles would be great.
  2. jcsd
  3. Jan 6, 2006 #2
    You can use trigonometry to find the horizontal and the vertical components of both vectors, and then you can add the two horizontal components together and add the two vertical components together. If you do this, you will get the vertical and horizontal components of the new vector.
  4. Jan 6, 2006 #3


    Staff: Mentor

    If you can solve it with right triangles you can solve it with anything, just go backwards from what you are familiar with. Just look at e.g. the 18N 85ยบ vector as the hypotenuse of a right triangle with the opposite side parallel to the y axis and the adjacent side on the x axis. Do the same with the other vector. You should be able to go on from there the way you are already familiar with.

  5. Jan 6, 2006 #4
    Ok, thanks, but how will I find my angle. I can add and solve for a new triangle and get the N, but I don't know what to do for the degrees.
  6. Jan 6, 2006 #5
    you can solve for the angle using trigonometry. if you know the sides of the right triangle then you can find the angle.
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