Spot the odd one out

Exercise and reference answers

Questions

1. Items

   1. Distance from the origin
   2. Cosine of angle with x-axis
   3. Cosine of angle with y-axis

   Odd item

   Distance from the origin

2. Items

   1. r = a + λb
   2. l² + m² + n² = 1
   3. r = a + λ(b − a)

   Odd item

   l² + m² + n² = 1

3. Items

   1. Skew
   2. Parallel
   3. Perpendicular
   4. Determinant

   Odd item

   Determinant

Explanation