Let's analyze each statement in the context of neutral geometry, which includes the axioms of Euclidean geometry except for the parallel postulate:

(a) Every angle has an angle bisector

• True. In neutral geometry, it is always possible to construct an angle bisector. This follows from basic geometric constructions using a compass and straightedge, which do not rely on the parallel postulate.

(b) For every triangle there is an inscribed circle

• False. The existence of an inscribed circle for every triangle requires properties related to the parallel postulate. In hyperbolic geometry (a form of non-Euclidean geometry that falls under neutral geometry), it is not guaranteed that every triangle has an inscribed circle.

(c) Every triangle has a circumscribed circle

• False. Similar to the case with the inscribed circle, the existence of a circumscribed circle for every triangle depends on the parallel postulate. In neutral geometry, there is no guarantee that a triangle can be circumscribed by a circle, especially in hyperbolic space.

Summary:

• (a) is true in neutral geometry.
• (b) and (c) are false in neutral geometry.

Would you like further details or have any questions about this?

Here are five related questions that expand on this topic:

1. What are some key differences between Euclidean and non-Euclidean geometry?
2. Why does the parallel postulate play a crucial role in Euclidean geometry?
3. How is angle bisector construction achieved using only compass and straightedge?
4. What are the properties of hyperbolic geometry that differ from Euclidean?
5. Can you provide examples of triangles that do not have an inscribed or circumscribed circle in hyperbolic geometry?

Tip: In neutral geometry, many familiar theorems from Euclidean geometry hold, except those that depend explicitly on the parallel postulate.