**1. What if the scalar product of two vectors is zero?**

If the scalar product of two vectors is zero this means that the two vectors are perpendicular or cross at right angles.

**2. Can the scalar product be used for three dimensional vectors?**

Yes, the methods used are the same as those used for two dimensional vectors.

**3. Can the ratio theorem be used to find the mid-point of a line?**

Yes, the values of λ and μ simply become 1/2 and 1/2.