Identify and Classify Triangles Worksheets - K12 Math Worksheets - Free Printable

To classify each triangle by its angles, we need to remember:

- Acute triangle: All three angles are less than 90°.
- Right triangle: One angle is exactly 90°.
- Obtuse triangle: One angle is greater than 90°.

We’ll go row by row, left to right.

---

Row 1:

1. First triangle (top-left): Looks like all angles are sharp — no wide or square corner → Acute
2. Second triangle (top-middle): Also looks like all angles are small and sharp → Acute
3. Third triangle (top-right): Has a clear square corner (like the corner of a book) → Right

---

Row 2:

4. Fourth triangle (middle-left): One angle is very wide — bigger than a right angle → Obtuse
5. Fifth triangle (middle-center): All angles look sharp again → Acute
6. Sixth triangle (middle-right): One angle is clearly wide and open → Obtuse

---

Row 3:

7. Seventh triangle (bottom-left): Has a square corner → Right
8. Eighth triangle (bottom-middle): Also has a square corner → Right
9. Ninth triangle (bottom-right): All angles are narrow and sharp → Acute

---

Let’s double-check:

- Acute: #1, #2, #5, #9 → 4 triangles
- Right: #3, #7, #8 → 3 triangles
- Obtuse: #4, #6 → 2 triangles

Total = 9 → matches the number of triangles. Good!

Final Answer:
Acute, Acute, Right, Obtuse, Acute, Obtuse, Right, Right, Acute