Write a complete description of the locus of points that satisfy the given conditions.

I have three questions:

1. In a plane, 20 cm from point P, and 30 cm from point Q when PQ = 10 cm.

2. In space, 20 cm from point P, and 30 cm from point Q when PQ = 60cm.

3. In plane S and 10 m from point A, given that A is 6 m from plane S.