Knowledge and understanding of circle geometry relationships will help verify the techniques employed when constructing figures. Circle geometry also provides a context to apply the understanding of similar triangles with their associated proportions, as well as many other geometrical concepts.
It is particularly important to provide plenty of opportunities to explore the (many) angle and chord properties of circles.
Angle and chord properties
The first step in deductive reasoning in circle geometry is recognising the angle and chord properties. Ordering the relationships sequentially then forms the foundation of a proof.