Three of these are wrong. Find the one that holds.

Exercise and reference answers

Questions

1. Question

   Three of these statements about a · b are false.

   Choices

   1. Item

      It equals |a||b| cos θ

      Correct

      Yes

   2. Explanation

      Sine belongs to the cross product.

      Item

      It equals |a||b| sin θ

   3. Explanation

      The scalar product returns a number.

      Item

      It returns a vector

   4. Explanation

      A number has no direction to be perpendicular to.

      Item

      It is perpendicular to a and b

2. Question

   Three of these statements about the zero vector are false.

   Choices

   1. Item

      Its initial and terminal points coincide

      Correct

      Yes

   2. Explanation

      That describes a unit vector.

      Item

      It has magnitude 1

   3. Explanation

      It cannot be assigned any definite direction.

      Item

      It points along the x-axis

   4. Explanation

      Their magnitudes are 0 and 1 respectively.

      Item

      It is the same as a unit vector

Explanation