# Solving linear matrix equations

Hi everybody, I'm new to Sage and I'm pretty confused with the solving of matrix equations, I didn't fully understand the guide.

I've got these vectors:

```
V_fa = vector([V_f*cos(phi), V_f*sin(phi), 0])
V_ra = vector([V, 0, 0])
omega = vector([0, 0, L*psi_d])
P = vector([0, L*psi_d, 0])
```

And i want to implement the equation:

```
V_fa=V_ra+omega.cross_product(P)
```

to isolate and obtain the value of `psi_d`

.

How can I do that?

Thank you very much