1 | initial version |

I think you are asking for a system from this vector equation that you can then get Sage to solve. To create such a system, try:

```
ans1=V_ra+omega.cross_product(P)
sys=[ans1[i]==V_fa[i] for i in range(0,3)]
```

Then, you get the result:

```
[-L^2*psi_d^2 + V == V_f*cos(phi), 0 == V_f*sin(phi), 0 == 0]
```

Solving the first equation for `psi_d`

can be done by:

```
solve(sys[0],psi_d)
```

and gives:

```
[psi_d == -sqrt(-V_f*cos(phi) + V)/L, psi_d == sqrt(-V_f*cos(phi) + V)/L]
```

Sage does not seem to like the idea of solving all three equations at once. You might be able to avoid this by specifying more information about `phi`

.

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