# Just Tell Me If Its Doable (Vectors)

#### sugarntwiligh

Just Tell Me If Its "Doable" (Vectors)

Here's the problem:
Give magnitude and direction from the positive x axis, given A=60. Use the following picture:

http://www.webassign.net/giancoli5/3_35alt.gif

I know how to do vectors...
Ax: 60cos(28)=52.98
Ay: 60sin(28)=28.17

Cx: 0
Cy: 46.8

B: ?
B: ?

Now correct me if I am wrong, but don't I need the angle of B in order to solve?

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#### Doc Al

Mentor
Re: Just Tell Me If Its "Doable" (Vectors)

What's the exact statement of the problem?

#### sugarntwiligh

Re: Just Tell Me If Its "Doable" (Vectors)

What's the exact statement of the problem?
Determine the vector A - C, given the vectors A and C in Fig. 3-35 (A = 60.0).

Magnitude:_____
Direction:____ ° (from the positive x axis)

#### Doc Al

Mentor
Re: Just Tell Me If Its "Doable" (Vectors)

Determine the vector A - C, given the vectors A and C in Fig. 3-35 (A = 60.0).
This has nothing to do with B, so B's angle is not needed.

I know how to do vectors...
Ax: 60cos(28)=52.98
Ay: 60sin(28)=28.17

Cx: 0
Cy: 46.8
Good, except for the sign of Cy.

#### sugarntwiligh

Re: Just Tell Me If Its "Doable" (Vectors)

This has nothing to do with B, so B's angle is not needed.

Good, except for the sign of Cy.
Oh ok I got it now. Since its A-C, I just take my C values and times them by -1. So now I have,
C=-46.8(-1)=46.8 (y)
C=0 (x)

And then I take the values Rx and Ry:

Rx: 52.98
Ry: 74.97

And plug in the formula:

squareroot(52.98^2+74.97^2)=91.8

And I get my angle:

tan-1(74.97/52.98)=54.8

Yay!!!

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