1. **State the problem:** Classify each triangle based on its angles as acute, obtuse, or right. 2. **Recall definitions:** - A **right triangle** has one angle exactly $90^\circ$. - An **obtuse triangle** has one angle greater than $90^\circ$. - An **acute triangle** has all angles less than $90^\circ$. 3. **Analyze each triangle:** - Triangle 1 (45°, 90°, 45°): One angle is $90^\circ$, so it is a **right triangle**. - Triangle 2 (60°, 60°, 60°): All angles are $60^\circ < 90^\circ$, so it is an **acute triangle** (specifically equilateral). - Triangle 3 (140°, 40°, 10°): One angle is $140^\circ > 90^\circ$, so it is an **obtuse triangle**. - Triangle 4 (50°, 92°, 38°): One angle is $92^\circ > 90^\circ$, so it is an **obtuse triangle**. - Triangle 5 (40°, 60°, 80°): All angles less than $90^\circ$, so it is an **acute triangle**. - Triangle 6 (60°, 50°, 70°): All angles less than $90^\circ$, so it is an **acute triangle**. 4. **Summary:** - Triangle 1: Right - Triangle 2: Acute - Triangle 3: Obtuse - Triangle 4: Obtuse - Triangle 5: Acute - Triangle 6: Acute This classification is based on the angle measures and the definitions of triangle types.