Hi

A vector has x, y, and z components of Ax, Ay, and Az. I want to calculate the angle between the vector and the x-axis (call it theta).

I work out the following:

sqrt(Ax*Ax + Az*Az) * cos(theta) = Az

sqrt(Ax*Ax + Az*Az) * sin(theta) = Ax

So that theta = arctan(Ax/Az).

But the notes I have state a different equation for theta:

theta = arctan(Ax / sqrt(Az*Az + Ay*Ay))

Could you please tell me where I am going wrong, and how the notes get the answer?

Thanks.