Question

which name can be used for the 20° angle? ∠etv ∠evn ∠evt ∠nvt

Explanation:

Step1: Understand angle - naming rules

An angle can be named in three ways: by its vertex (if there is only one angle at that vertex), by three points where the vertex is the middle point.

Step2: Analyze each option

• For \(\angle ETV\): The vertex should be \(V\) for the \(20^{\circ}\) angle. In \(\angle ETV\), the vertex is \(T\), so this is incorrect.
• For \(\angle EVN\): The angle \(\angle EVN\) is a right - angle (\(90^{\circ}\)) as indicated in the diagram, not the \(20^{\circ}\) angle.
• For \(\angle EVT\): The vertex is \(V\), and the two rays forming the angle are \(VE\) and \(VT\). This is the correct way to name the \(20^{\circ}\) angle using three - point notation (vertex in the middle).
• For \(\angle NVT\): The angle \(\angle NVT\) is a combination of the \(90^{\circ}\) angle and the \(20^{\circ}\) angle (if we consider the adjacent angles at vertex \(V\)), so it is not the \(20^{\circ}\) angle.

Answer:

\(\angle EVT\)