# Adding vectors. Angle of vector or resultant

• Mar 13th 2011, 04:33 PM
bdika
Adding vectors. Angle of vector or resultant
Could someone please try and explain to me how to interpret the angle of the resultant when adding or subtracting 2 vectors? I do not have any trouble in using the cosine law to calculate the magnitude of the resultant or the sine law to determine the various angles, but I cannot understand how to interpret the angle of the resultant, using either a true bearing or a quadrant bearing.

I've searched these forums but the concept is still not cleared up in my mind. For example in this thread http://www.mathhelpforum.com/math-he...or-147360.html
I cannot understand how the original poster's answer of N59.1degreesW ties into the respondent's figures of "42 degrees East of North" or further on in the post "The angle is given by [tex]tan^{-1}(27.36}{50.17}= 28.6 degrees".

In earboth's diagram and explanation I understand how he calculated the 58.666 degrees between the black line and the red line but I do not understand how that ties in to the direction the wind is blowing being "206.666 degrees or S26.666°W" according to earboth (although I do understand the translation from 206.666 degrees to S26.666°W)

Attachment 21139

I feel there is a basic hole in my understanding of vector direction that is preventing me from being able to interpret these directions.

Is there a simple way to figure out the direction or is it something a little more complicated?

Any help would be much appreciated. If you can see what I am misinterpreting I would very much appreciate if you could throw some light on it for me. Any explanation on the subject would be welcome even if it does not refer to the linked threads.

Sorry if the answer is very obvious.

Thank you.

bdika
• Mar 13th 2011, 05:13 PM
skeeter
Quote:

Originally Posted by bdika