Question

after another wind change, the weathervane has turned an additional 20° and stopped at point t. which name can be used for the 20° angle? ∠etv ∠evn ∠evt ∠nvt

Explanation:

To name an angle, we use the middle letter to represent the vertex of the angle, and the other two letters represent the points on the two sides of the angle.

1. First, identify the vertex of the \(20^{\circ}\) angle. From the diagram, the vertex is \(V\).
2. Then, identify the two points on the sides of the angle. The two sides of the \(20^{\circ}\) angle pass through points \(E\) and \(T\) (with \(V\) as the vertex).
3. When naming an angle, the vertex letter should be in the middle. So we check the options:

• For \(\angle ETV\), the vertex is \(T\), which is incorrect.
• For \(\angle EVN\), the angle formed is not the \(20^{\circ}\) angle (it would be related to the \(90^{\circ}\) or other angles in the diagram).
• For \(\angle EVT\), the vertex is \(V\), and the sides pass through \(E\) and \(T\), which matches the \(20^{\circ}\) angle.

Answer:

\(\boldsymbol{\angle EVT}\)