Question

1. which is not a correct name for the angle? a) ∠1 b) ∠pxh c) ∠phx d) ∠x

Explanation:

Step1: Recall angle - naming rules

An angle can be named by a number inside the angle (∠1), by the vertex letter when there is only one angle at the vertex (∠X), or by three points where the vertex is the middle - point (∠PXH).

Step2: Analyze each option

• Option A: ∠1 is a valid name as it uses the number inside the angle.
• Option B: ∠PXH is a valid name as it follows the three - point naming convention with X as the vertex.
• Option C: ∠PHX is not a valid name for this angle. In the three - point naming convention for an angle, the vertex must be the middle letter. Here, the vertex of the given angle is X, not H.
• Option D: ∠X is a valid name since there is only one angle at vertex X.

Answer:

C. ∠PHX