# Adding vector components

## Homework Statement

I read how to solve a problem I am working on, and part of it deals with adding vector components. A is the vector, Ax is the x component, Ay the y component, and theta is the angle A makes from the y axis.

## The Attempt at a Solution

The solution involves using Ax Sin(theta) + Ay Cos(theta) = A.

I know it seems easy but I can't seem to figure out why this would be true?

## Answers and Replies

The solution involves using Ax Sin(theta) + Ay Cos(theta) = A.

I know it seems easy but I can't seem to figure out why this would be true?

This actually doesn't make sense if A is a scalar.

When you add vectors you get vectors not scalars.

If you were referring to $$\left\|A_x Sin(\theta) + A_y Cos(\theta) \right\| =A$$ then that would make more sense.

What I mean was Ax Sin(theta) + Ay Cos(theta) = A where A, Ax and Ay are vectors, I don't see where this relation comes from?

In what direction is A,if it is a vector ? The only way this would make sense is if A has the direction of a_rho in cylindrical coordinates.

So I have to ask... in what direction is the unit vector of A?

HallsofIvy