What are two angles that share a vertex and a side referred to as?

Two angles that share a vertex and a side are referred to as adjacent angles. This definition is key in geometry, as adjacent angles are positioned next to each other, forming a larger angle when combined. They do not overlap and their non-shared sides are rays that extend away from the vertex.

Understanding the concept of adjacent angles is foundational for more complex geometrical principles. For instance, when discussing angles formed at intersections or within shapes, recognizing adjacent angles enables students to visualize and calculate angle measures effectively.

While interior angles refer specifically to angles formed within a polygon, complementary angles are those that add up to 90 degrees, and supplementary angles add up to 180 degrees. None of these terms captures the shared vertex and side characteristic that defines adjacent angles.