Identifying Types of Triangles - Worksheet - Acute, Obtuse, Right & Equilateral, Isosceles, Scalene

Sep 30, 2026

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Identifying Types of Triangles provides student practice for classifying triangles by both angle measure and side/angle equality. The page defines acute, obtuse, and right triangles, then identifies equilateral, isosceles, and scalene triangles based on equal sides and equal angles. Problems ask learners to determine the letter labels (A/O/R and E/I/S) for multiple numbered triangles. Answer key information is included on the provided materials.

LanguageEnglish

CategoryExam

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Determine Triangle Types

Classify by Angles (Acute, Obtuse, Right)

Classify by Sides/Angles (Equilateral, Isosceles, Scalene)

Answer Key

Identifying Types of Triangles Name: | Determine if each triangle is acute(A), obtuse(O) or right(R) and if it is an

equilateral(E), isosceles(I) or scalene(S). Acute Triangle:
All angles are less than 90° .
Obtuse Triangle:
One angle is greater than 90° .
Right Triangle:
One angle is 90° .
Equilateral Triangle:
3 equal sides. 3 equal angles.
Isosceles Triangle:
2 equal sides. 2 equal angles.
Scalene Triangle:
No equal sides. No equal angles.

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8. | | Answers | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1-8 | 88 | 75 | 63 | 50 | | 38 | 25 | 13 | 0 | [Math](Math www.CommonCoreSheets.com 4)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 4)[ 4](Math www.CommonCoreSheets.com 4) Identifying Types of Triangles Name: Answer Key | Determine if each triangle is acute(A), obtuse(O) or right(R) and if it is an

equilateral(E), isosceles(I) or scalene(S). Acute Triangle:
All angles are less than 90° .
Obtuse Triangle:
One angle is greater than 90° .
Right Triangle:
One angle is 90° .
Equilateral Triangle:
3 equal sides. 3 equal angles.
Isosceles Triangle:
2 equal sides. 2 equal angles.
Scalene Triangle:
No equal sides. No equal angles.

| | | | | Answers 1. O S 2. O I 3. R S 4. A E 5. A S 6. O I 7. R I 8. A I | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | 1)
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92
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78
~~ 150 ~~
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92

169
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80
80
136 | | | | | | | | | | | |

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150
8) | | | | | | | | | | | 1-8 | | | 88 | 75 | 63 | 50 | 38 | 25 | 13 | 0 | [Math](Math www.CommonCoreSheets.com 4)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 4)[ 4](Math www.CommonCoreSheets.com 4) Identifying Types of Triangles Name: | Determine if each triangle is acute(A), obtuse(O) or right(R) and if it is an

equilateral(E), isosceles(I) or scalene(S). Acute Triangle:
All angles are less than 90° .
Obtuse Triangle:
One angle is greater than 90° .
Right Triangle:
One angle is 90° .
Equilateral Triangle:
3 equal sides. 3 equal angles.
Isosceles Triangle:
2 equal sides. 2 equal angles.
Scalene Triangle:
No equal sides. No equal angles.

1)
3)
5)

2)
4)
6)

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6. | | Answers | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1-6 | 83 | 67 | | 50 | 33 | 17 | 0 | Math Modified [www.CommonCoreSheets.com](www.CommonCoreSheets.com) 4

FAQs

How do you identify an acute, obtuse, or right triangle?

An acute triangle has all angles less than 90°. An obtuse triangle has one angle greater than 90°. A right triangle has one angle equal to 90°.

How do you identify equilateral, isosceles, and scalene triangles?

An equilateral triangle has 3 equal sides and 3 equal angles. An isosceles triangle has 2 equal sides and 2 equal angles. A scalene triangle has no equal sides and no equal angles.

What do the worksheet questions ask you to do?

Each numbered item asks whether the given triangle is acute (A), obtuse (O), or right (R), and whether it is equilateral (E), isosceles (I), or scalene (S).

Is there an answer key included?

Yes. The provided materials include an answer key listing the classifications for each problem number.

Sep 30, 2026

Uploaded by Fans