Three Vectors - Resultant vector magnitude?

[KendrickLamar]

Homework Statement

Three vectors are shown in the figure (A = 68.0 ; qB = 54.0°). Their magnitudes are given in arbitrary units. What is the magnitude of the resultant vector?

Homework Equations

here's the image that goes with it

The Attempt at a Solution

well i figure the angle would be 98 then i guess I am just looking for the missing side which is the resultant vector but i tried some trig functions and failed, not really sure what to do, this is pretty basic but i haven't looked at any physics in about 3-4 years.

thanks if u can help

 

[rock.freak667]

The easiest way would be to split B and A into both vertical and horizontal components. Then find the sum of the vertical (y) and sum of the horizontal (x) then apply

$$R=\sqrt{x^2+y^2}$$

Do you know remember how to split a vector into components?

 

[KendrickLamar]

The easiest way would be to split B and A into both vertical and horizontal components. Then find the sum of the vertical (y) and sum of the horizontal (x) then apply

$$R=\sqrt{x^2+y^2}$$

Do you know remember how to split a vector into components?

haha not really i feel kinda dumb now, can u quickly remind me? but even if u split it, and you're trying to get that other side, can't u NOT use the pythagorean theorem since there's no right angle

 

[rock.freak667]

haha not really i feel kinda dumb now, can u quickly remind me? but even if u split it, and you're trying to get that other side, can't u NOT use the pythagorean theorem since there's no right angle

How to split them: http://www.grc.nasa.gov/WWW/k-12/airplane/vectpart.html"


You would be splitting them into horizontal and vertical vectors so the right angle is always there.

Once you split all into horizontal and vertical, you can sum the individual verticals to get the resultant vertical (y) and similarly sum the horizontals to get the resultant horizontal (x). Then apply the formula.

 

[KendrickLamar]

what i don't get is, after u split it what are u exactly looking for because then you're just solving for A and B which are already given to you? A= 68 B =40 so wouldn't the purpose of splitting it into components be to get those values, however they're already provided.

 

[rock.freak667]

what i don't get is, after u split it what are u exactly looking for because then you're just solving for A and B which are already given to you? A= 68 B =40 so wouldn't the purpose of splitting it into components be to get those values, however they're already provided.

You are give A and B at the particular angles, if you split into the components then you get the resultants in the x and y directions, which is what you want.