Classify Angle ABC: Identifying an Angle Less Than 90 Degrees

To determine what kind of angle $\angle \text{ABC}$ is, let's examine the given information: the angle is less than $90^\circ$.

• Step 1: Recall the types of angles based on their measurements:
• An acute angle measures less than $90^\circ$.
• A right angle measures exactly $90^\circ$.
• An obtuse angle measures greater than $90^\circ$ but less than $180^\circ$.
• A flat angle measures exactly $180^\circ$.
• Step 2: Match the given information with these definitions.

Since $\angle \text{ABC}$ measures less than $90^\circ$, it fits the definition of an acute angle.

Therefore, the angle $\angle \text{ABC}$ is an acute angle.