# Calculate A and B (Vector) [closed]

The diagram below shows two vectors, A and B, and their angles relative to the coordinate axes as indicated.

DATA: alpha = 42.7 degrees, beta = 56.8 degrees, A = 6.70 cm. The vector A - B is parallel to the -x axis (points due West). Calculate the y component of vector B.

i) Calculate the x component of the vector A -B

ii) Calculate the magnitude of the vector A + B

I used the following approach to get A and B but the CAPA online assignment system says its wrong.

A = (AxCos(α), AxSin(α))

B = (BxSin(β), BxCos(β))

we have α and A so we have the x and y components of A. then we know y component of (A-B) must be zero cause (A-B) is parallel to x-axis so we know the y-component of B (which is equal to y-component of A) so we say AxSin(α) = BxCos(β) and we get the magnitude of B now we can calculate the x-component of B as well as I followed:

A = (AxCos(α), AxSin(α)) = (6.70 x Cos(42.7), 6.70 x Sin(42.7)) = (-4.9239, -4.5436)

and y-component of B must be -4.5436 so

-4.5436 = B x Cos (56.8) => B = -4.5436/Cos(56.8) => B = 8.2978

and so B = (8.2978, -4.5436)

and so -B = (-8.2978, +4.5436)

would you please tell me were I am wrong?

Sincerely,

Peyman

-
Hi Peyman, and welcome to Physics Stack Exchange! Generally we discourage questions that just ask for someone to check your work. Once you have identified the specific concept that you're not sure about, that's the point at which it's appropriate to ask a question here. You may find some of the information in our homework policy helpful. – David Zaslavsky Sep 18 '12 at 23:22

## closed as too localized by David Zaslavsky♦Sep 18 '12 at 23:21

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, see the FAQ.