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Two vectors A and B, are lying in the xy

plane and given by

A = Axi +Ayj

B = Bxi +Byj

(x y are subscripts)

where A x = 4.4 m, A y = 1.74 m, B x = 7.58 m, B y = -6.76 m. Let R = A+B.

Find the magnitude of R. Answer in units

of m.

So it is

A = 4.4mI + 1.74mJ

B = 7.58mI - 5.02J

I have found out R by using the distance formula

sqrt(11.98^2 + 5.02^2) = 12.9893 m(which is right)

part 2 of 2

Find the angle that the vector R makes from

the positive x axis. Choose your answer to be

between -180 # and +180 # . The positive an_

gular direction is counter clockwise measured

from the x axis. Answer in units of # .

I tried this problem using the cosine law.

-5.02squared-11.98squared-12.99squared

______________________________________(division)

-2*11.98*12.99

I got 22.73 degrees. But when I sumbit this answer, it says I'm wrong. Can you figure out what I'm doing wrong?