Identifying Types of Triangles - Answer Key - Determine Acute(A), Obtuse(O) or Right(R) and Equilateral(E), Isosceles(I) or Scalene(S)

Sep 30, 2026

Uploaded by Fans

Worksheet content focuses on identifying triangle types by classifying each figure by angle—acute (all angles less than 90°), obtuse (one angle greater than 90°), or right (one angle equals 90°)—and by side symmetry—equilateral (3 equal sides and angles), isosceles (2 equal sides and angles), or scalene (no equal sides or equal angles). An included answer key lists the correct classifications for numbered triangles 1 through 8, supporting self-check and assessment.

LanguageEnglish

CategoryExam

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Identify Triangle Angle Type

Acute, Obtuse, Right

Identify Triangle Side Type

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 3)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 3)[ 3](Math www.CommonCoreSheets.com 3) 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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3)

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104 163 | | | Answers 1. R S 2. A I 3. O I 4. A S 5. A E 6. R I 7. O S 8. O I | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | 1-8 | 88 | 75 | 63 | 50 | 38 | 25 | 13 | 0 | [Math](Math www.CommonCoreSheets.com 3)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 3)[ 3](Math www.CommonCoreSheets.com 3) 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) 3

FAQs

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

Use the angle measure rules: acute triangles have all angles less than 90°, obtuse triangles have one angle greater than 90°, and right triangles have one angle equal to 90°.

What makes a triangle 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.

Where can the correct classifications be found for each numbered triangle?

The document includes an “Answer Key” section listing the correct A/O/R and E/I/S codes for triangles 1 through 8.

Sep 30, 2026

Uploaded by Fans