Identifying Types of Triangles - Answer Key - Determine Acute/Obtuse/Right and Equilateral/Isosceles/Scalene

Sep 30, 2026

Uploaded by Fans

Worksheet answer key for identifying triangle types by both angle measure and side length classification. It specifies how to distinguish acute, obtuse, and right triangles using comparisons to 90° angles, and how to recognize equilateral, isosceles, and scalene triangles based on equal sides and equal angles. The key provides the coded answer pairs (A/O/R and E/I/S) for numbered problems.

LanguageEnglish

CategoryExam

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Determine Triangle Categories

Angle-based classification (A/O/R)

Side-based classification (E/I/S)

Answer Key (1-8)

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 6)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 6)[ 6](Math www.CommonCoreSheets.com 6) 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.

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150 | | | Answers 1. O I 2. R S 3. O S 4. O I 5. A S 6. A I 7. R I 8. A E | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | 1-8 | 88 | 75 | 63 | 50 | 38 | 25 | 13 | 0 | [Math](Math www.CommonCoreSheets.com 6)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 6)[ 6](Math www.CommonCoreSheets.com 6) 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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6. | | Answers | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1-6 | 83 | 67 | | 50 | 33 | 17 | 0 | Math Modified [www.CommonCoreSheets.com](www.CommonCoreSheets.com) 6

FAQs

How do you determine whether a triangle is acute, obtuse, or right?

Acute triangles have all angles less than 90°. Obtuse triangles have one angle greater than 90°. Right triangles have one angle equal to 90°.

How do you classify a triangle as equilateral, isosceles, or scalene?

Equilateral triangles have 3 equal sides (and 3 equal angles). Isosceles triangles have 2 equal sides (and 2 equal angles). Scalene triangles have no equal sides (and no equal angles).

What information does the answer key provide?

For each numbered item, it lists the correct classification codes for angle type (A/O/R) and side type (E/I/S) together as answers.

Sep 30, 2026

Uploaded by Fans