In the context of right triangles, how do rays $ab$ and $ac$ relate to the formation of an angle at vertex $a$?

• A. The rays $ab$ and $ac$ do not share a common endpoint and therefore cannot form an angle.
• B. The rays $ab$ and $ac$ are parallel and do not form an angle at $a$.
• C. The rays $ab$ and $ac$ share a common endpoint at $a$, forming an angle at $a$ where the space between the rays is measured as the angle.
• D. The rays $ab$ and $ac$ form a straight line, so the angle at $a$ is always $180°$.

Answer: (C)

Verified step by step guidance

1. Identify the rays involved: ray \(ab\) and ray \(ac\). Both rays start from the point \(a\), which is their common endpoint or vertex.
2. Recall the definition of an angle: an angle is formed by two rays that share a common endpoint. The vertex of the angle is this common endpoint.
3. Since rays \(ab\) and \(ac\) both originate from point \(a\), they share the common endpoint \(a\), which means they form an angle at vertex \(a\).
4. The measure of the angle at \(a\) is the amount of rotation or space between ray \(ab\) and ray \(ac\). This is the angle formed by these two rays.
5. Therefore, the rays \(ab\) and \(ac\) are not parallel or disconnected; instead, they create an angle at \(a\) by sharing the vertex \(a\).