Question

what is an angle that is adjacent to ∠dea?

Explanation:

Step1: Recall adjacent angle definition

Adjacent angles share a common side and vertex, and their non - common sides are opposite rays or form a linear pair (supplementary). For $\angle DEA$, the vertex is $E$, and one side is $ED$. The other side is $EA$.

Step2: Identify adjacent angles

Looking at the intersection of the lines at $E$, an angle that shares the common side $ED$ (or $EA$) and vertex $E$ with $\angle DEA$ is $\angle DEB$ (or $\angle AEC$). Let's take $\angle DEB$: it shares the side $ED$ and vertex $E$ with $\angle DEA$, and the non - common sides $EA$ and $EB$ are opposite rays (since $A$, $E$, $C$ are colinear and $D$, $E$, $B$ are colinear). Another option is $\angle AEC$, which shares the side $EA$ and vertex $E$ with $\angle DEA$, and the non - common sides $ED$ and $EC$ are opposite rays.

Answer:

$\angle DEB$ (or $\angle AEC$)