### add a plane defined by two vectors

I have a set of three vectors

```
p1 = vector([1,-0.5,0]) # eigenvector of eigenvalue 2
p2 = vector([0,0,1]) # eigenvector of eigenvalue 2
c = vector([1,-1,0]) # eigenvector of eigenvalue 3
plot(p1, color = "red") + plot(p2, color = "red") + plot(c)
```

Vectors `p1`

and ~~p2` ~~`p2`

form a plane since they come from the same eigenvalue. How would I add a plane defined by these two vectors?