Questions on Algebra: Introduction to vectors, addition and scaling answered by real tutors!

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Question 96832: Hallo,
my question is, when we add two or more vectors algebraically in two dimension, how can we find the direction of the resultant vector.
Thanks, Hamad
: Hallo,
my question is, when we add two or more vectors algebraically in two dimension, how can we find the direction of the resultant vector.
Thanks, Hamad

Answer by stanbon(19007) About Me  (Show Source):
You can put this solution on YOUR website!
If you have vectors (2,3) and (-1,6)
Add the corresponding x and y values to get:
(1,9)
Then the angle is tan^-1(9/1) = 83.66 degrees
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Be careful when you take the tan^-1; you must
remember tan^-1 has a restricted range.
Visualize where your resultant is so you get
the proper angle.
For example:
If the resultant is (-3,-5), tan^-1(-5/-3) = 59.036.. degrees.
But that resultant is in the 3rd quadrant. The angle you
want is 180+59.036 = 239.036 degrees.
=============
Cheers,
Stan H.