Calc 3 - Vectors: Find magnitude, direction of resultant

[Jamers328]

Here is the problem:

a) Give the vector whose length is 15 units and that makes an angle of -40 degrees with the positive x-axis.

b) Suppose that a vector which is 20 units long in the direction of the positive y-axis is added to the vector you just got in part a. Give the magnitude and direction of the resultant vector. (Approximate to 3 decimal places).

I already got the correct answer to part a, which is <11.49, -9.645>.

I have the picture drawn correctly (or so I hope) for part b, but I do not know how to find the magnitude and direction for the resultant vector (which I have drawn in quadrant 1).

Any ideas?

Sorry if I was at all confusing, please ask any questions and I will do my best to clarify!

 

[xXAceFireXx]

20 units in y dir would be <0,20>

u just add that to the other vector that you got to get the resultant vector.

 

[Jamers328]

What about the direction?

Thank you.

 

[Deleted member 4993]

If the vector (a,b) makes an angle ß with x- axis, then

cos ß = a/\(\displaystyle sqrt{a^2 + b^2}\)