Question

which angles are adjacent to each other? ∠1 and ∠8 ∠4 and ∠2 ∠10 and ∠9 ∠8 and ∠12

Explanation:

Step1: Recall adjacent - angle definition

Adjacent angles share a common side and a common vertex and have no interior points in common.

Step2: Analyze each pair

• For $\angle1$ and $\angle8$: They do not share a common side or vertex, so they are not adjacent.
• For $\angle4$ and $\angle2$: They share a common vertex and a common side, so they are adjacent.
• For $\angle10$ and $\angle9$: They share a common vertex and a common side, so they are adjacent.
• For $\angle8$ and $\angle12$: They do not share a common side or vertex, so they are not adjacent.

Answer:

$\angle4$ and $\angle2$, $\angle10$ and $\angle9$