It's not exactly homework as it's a progress check question in a home learning course but I think this is the best place for it.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

The question I have is:

Calculate the resultant of the two vectors shown:

[PLAIN]http://www.mattvonfat.com/question.png [Broken]

3. The attempt at a solution

Here's my problem, I've come up with the magnitude of the resultant as 116.037N and the direction 10.04° below the horizontal. The course gives the answer as 76.97N at 15.24° below the horizontal.

I've gone over the material again however it seems that the answer the course book gives is still wrong. I also tried putting the vectors in to the vector addition applets and calculators on web pages but they don't give the answer the course gives me either.

Here's how I worked it:

Is there a problem with they way I have done it or is the course wrong?Code (Text):

Horizontal Component of 60N vector = 60cos 35

= 49.15N

Vertical Component of 60N Vector = 60sin 35

= 34.41N

Horizontal Component of 85N vector = 85cos 40

= 65.11N

Vertical Component of 85N vector = -85sin 40

= -54.64N

Total Horizontal = 49.15 + 65.11 = 114.26N

Total Vertical = 34.41 - 54.64 = -20.23N

Then I use those values for the sides of a right angled triangle and the hypotenuse/magnitude of the vector is:

h² = 114.26² + -20.23²

h² = 13464.6

h = 116.037N

and the angle (a):

Tan a = -20.23 / 114.26

a = Tan[SUP]-1[/SUP] 0.177

a = -10.04°

Thanks for any help you can offer,

Matthew

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# Homework Help: Combining Vectors

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