Answer:
The correct option is 2. The vertex of the angle is RST is S.
Step-by-step explanation:
If an angle is measured about a point, then the point is called angle's vertex, and the angle associated with that vertex is called the vertex angle.
In other words the vertex of ∠abc is b.
From the given figure it is clear that the vertex angle is l and angle RST is measured about a point S. So the vertex of the angle is S.
[tex]\text{Vertex of }\angle RST=S[/tex]
The vertex of the angle is RST is S. Therefore the correct option is 2.
