Question: User: multiplying horizontal directions
1. The problem is to understand what happens when multiplying horizontal directions.
2. In mathematics and physics, directions are often represented as vectors.
3. Multiplying directions can mean multiplying vectors, which involves operations like the dot product or cross product.
4. The dot product of two horizontal direction vectors $\vec{a}$ and $\vec{b}$ is given by $$\vec{a} \cdot \vec{b} = |\vec{a}| |\vec{b}| \cos(\theta)$$ where $\theta$ is the angle between them.
5. If both directions are horizontal and aligned, $\theta = 0$, so $$\cos(0) = 1$$ and the dot product is simply the product of their magnitudes.
6. The cross product of two horizontal vectors results in a vector perpendicular to the horizontal plane.
7. Therefore, multiplying horizontal directions depends on the operation: dot product yields a scalar, cross product yields a vertical vector.
Final answer: Multiplying horizontal directions using the dot product gives a scalar equal to the product of their magnitudes if aligned; using the cross product gives a vector perpendicular to the horizontal plane.