Question 1120998
1.(a) describe the locus of points in a plane 3 cm from the points on a circle 
  with radius 8 cm
=============
Too vague.
Is the plane parallel to the plane of the given circle?
If not, the radius of the circle is not relevant.
Do you mean 3 cms from any point on the circle?
===============
 (b) sketch the locus of points for the air valve on the tire of a bicycle as the bicycle moves down a straight path.
---
Google cycloid, epicycloid, etc.