The standard vector equation for a plane is represented as $N \cdot X = d$. In this equation:
The given plane equation is $W^T \cdot X = 1$. By comparing this to the general form $N \cdot X = d$, we can identify that the vector $W^T$ corresponds to the normal vector $N$. The constant $d$ is equal to $1$.
We are provided with the vector $W^T = [1, 2, 3]$. Consequently, the normal vector to the plane defined by $W^T \cdot X = 1$ is this vector $W^T$ itself, which is $[1, 2, 3]^T$.
The question asks us to identify the vector that is normal to the plane. We have established that the normal vector is $W^T = [1, 2, 3]^T$. We now need to find which of the given options matches this vector.
| Option Number | Vector Given | Is it Equal to $[1, 2, 3]^T$? |
|---|---|---|
| 1 | $[-2, -2, 2]^T$ |
No |
| 2 | $[3, 0, -1]^T$ |
No |
| 3 | $[3, 2, 1]^T$ |
No |
| 4 | $[1, 2, 3]^T$ |
Yes |
| 5 | (No vector specified) | N/A |
The comparison shows that Option 4, represented by the vector $[1, 2, 3]^T$, is the one that exactly matches the calculated normal vector $W^T$.