1. Show a^2 b^2 =a.b a.b+a ^ b . a ^ b

2. A plane with position vectors a, b and c, find the distance of a fourth, with position vector r, from the plane.

3. A plane with the point (1, -2, 1) and the liner= (1+3?)i+ (?-1)j- 2?k. Find the distance of the plane from the origin.

If someone could start me off in the right direction that would be great.