To determine which of the given statements is a postulate, we need to understand the nature of postulates.
A postulate is a statement that is accepted as true without proof. Postulates serve as the foundational building blocks for a logical and mathematical system.
Let's analyze each statement:
1. Statement #1: "A line contains at least two points."
- This is a fundamental concept in geometry. It is an assumption that we accept without proof and use as a basis for further geometric reasoning.
2. Statement #2: "All right angles are equal."
- This is also a fundamental concept in geometry. It is an accepted truth that does not require proof and is used in the study of angles and shapes.
3. Statement #3: [tex]\( a + b = b + a \)[/tex]
- This is the commutative property of addition, which is a proven property in mathematics. It is not a postulate because it can be derived from the axioms of arithmetic.
Based on our understanding, Statement #1 is a postulate because it is an accepted fundamental idea without proof, forming the basis of geometric reasoning.
Therefore, Statement # [tex]$\boxed{1}$[/tex] is a postulate.
