Answer:
∠AXB or ∠PXQ or ∠AXQ or ∠PXB or ...
Step-by-step explanation:
A vertical angle is formed from the rays that are opposite the rays that form the original angle.
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opposite rays
The rays forming angle CXD are rays XC and XD. The ray opposite XC will have end point X, and can be named by either of the two points shown on the ray: A or P. That is, rays XA and XP are opposite ray XC.
Similarly, rays XB and XQ are opposite ray XD.
vertical angle
The vertical angle can be named using either of the first pair of opposite rays with either of the second pair:
∠AXB, ∠PXB, ∠AXQ, ∠PXQ
Of course, the ray names can be reversed in the angle names:
∠BXA, ∠BXP, ∠QXA, ∠QXP
Altogether, there are 8 ways to name the vertical angle to ∠CXD.
