Classify triangles by side lengths and angle measurements with this educational worksheet.

Let’s solve this step by step. The task is to classify each triangle using two criteria:

1. By side lengths: Equilateral, Isosceles, or Scalene
2. By angle measurements: Acute, Right, or Obtuse

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## 🔷 Definitions Recap:

✔ By Side Lengths:

- Equilateral: All three sides are equal.
- Isosceles: At least two sides are equal.
- Scalene: No sides are equal.

✔ By Angle Measurements:

- Acute: All three angles are less than 90°.
- Right: One angle is exactly 90° (marked with a square corner).
- Obtuse: One angle is greater than 90°.

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Now let’s classify each triangle one by one.

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## 🟦 First Set (Top Table)

a. Triangle a:

- Side lengths: No tick marks → all sides different → Scalene
- Angles: One angle looks >90° (obtuse) → Obtuse

✔ Answer: Scalene, Obtuse

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b. Triangle b:

- Side lengths: All three sides have tick marks → all equal → Equilateral
- Angles: In an equilateral triangle, all angles are 60° → Acute

✔ Answer: Equilateral, Acute

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c. Triangle c:

- Side lengths: Two sides have tick marks → two equal → Isosceles
- Angles: Has a right angle symbol → Right

✔ Answer: Isosceles, Right

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d. Triangle d:

- Side lengths: No tick marks → all sides different → Scalene
- Angles: One angle is clearly >90° → Obtuse

✔ Answer: Scalene, Obtuse

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## 🟩 Second Set (Bottom Table)

a. Triangle a:

- Side lengths: No tick marks → all sides different → Scalene
- Angles: Has a right angle symbol → Right

✔ Answer: Scalene, Right

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b. Triangle b:

- Side lengths: No tick marks → all sides different → Scalene
- Angles: One angle is clearly >90° → Obtuse

✔ Answer: Scalene, Obtuse

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c. Triangle c:

- Side lengths: Two sides have tick marks → two equal → Isosceles
- Angles: All angles look <90° → Acute

✔ Answer: Isosceles, Acute

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d. Triangle d:

- Side lengths: All three sides have tick marks → all equal → Equilateral
- Angles: All angles = 60° → Acute

✔ Answer: Equilateral, Acute

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## ✔ Final Answers Summary:

First Table:

| Triangle | Side Classification | Angle Classification |
|----------|----------------------|-----------------------|
| a | Scalene | Obtuse |
| b | Equilateral | Acute |
| c | Isosceles | Right |
| d | Scalene | Obtuse |

Second Table:

| Triangle | Side Classification | Angle Classification |
|----------|----------------------|-----------------------|
| a | Scalene | Right |
| b | Scalene | Obtuse |
| c | Isosceles | Acute |
| d | Equilateral | Acute |

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You can now circle the correct options in your worksheet based on this!

💡 Tip: Always check for tick marks (for sides) and the square symbol (for right angles) — they’re your visual clues!