Triangle Worksheets - Math Monks - Free Printable

I will solve this problem by classifying each of the 12 triangles based on their angles and sides as requested.

First, I need to understand the classification rules:
- By angles: Acute (all angles < 90°), Right (one angle = 90°), Obtuse (one angle > 90°)
- By sides: Equilateral (all sides equal), Isosceles (two sides equal), Scalene (all sides different)

Let me go through each triangle one by one.

Triangles 1-6: Classification by Angles

Triangle 1: Has a 90° angle → Right triangle
Triangle 2: All angles are 60° (< 90°) → Acute triangle
Triangle 3: Has a 140° angle (> 90°) → Obtuse triangle
Triangle 4: Has a 92° angle (> 90°) → Obtuse triangle
Triangle 5: All angles are 40°, 60°, 80° (all < 90°) → Acute triangle
Triangle 6: All angles are 50°, 60°, 70° (all < 90°) → Acute triangle

Triangles 7-12: Classification by Sides

Triangle 7: Sides are 4 cm, 5 cm, 6 cm (all different) → Scalene triangle
Triangle 8: Sides are 4.5 in, 6.5 in, 7.5 in (all different) → Scalene triangle
Triangle 9: Sides are 9 yd, 9 yd, 12 yd (two sides equal) → Isosceles triangle
Triangle 10: All sides are 4.5 cm (all equal) → Equilateral triangle
Triangle 11: Sides are 4 cm, 11 cm, 12 cm (all different) → Scalene triangle
Triangle 12: Sides are 3.5 cm, 3.5 cm, 6 cm (two sides equal) → Isosceles triangle

Now I'll provide the final answer with all classifications.

The completed worksheet would look like this:

Classify the triangles into acute, obtuse and right with given angles:
1. Right
2. Acute
3. Obtuse
4. Obtuse
5. Acute
6. Acute

Classify the triangles according to sides as equilateral, isosceles or scalene:
7. Scalene
8. Scalene
9. Isosceles
10. Equilateral
11. Scalene
12. Isosceles