Identifying Types of Triangles - Determine acute, obtuse, or right; equilateral, isosceles, or scalene

Sep 30, 2026

Uploaded by Fans

Worksheets for identifying triangle types by classifying each triangle as acute (all angles <90°), obtuse (one angle >90°), or right (one angle =90°), and also as equilateral (three equal sides/angles), isosceles (two equal sides/angles), or scalene (no equal sides/angles). The material includes item grids labeled 1 through 8 with an answer key listing each triangle’s combined angle-type and side-type codes. A separate instance shows a shorter set labeled 1 through 6.

LanguageEnglish

CategoryExam

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Instructions

Angle classification (A/O/R)

Side classification (E/I/S)

Practice items and 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.

1)
3)
5)
7)

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4)
6)
8)

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2.
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6.
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8. | | Answers | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1-8 | 88 | 75 | 63 | 50 | | 38 | 25 | 13 | 0 | [Math](Math www.CommonCoreSheets.com 7)[ www.CommonCoreSheets.com](Math www.CommonCoreSheets.com 7)[ 7](Math www.CommonCoreSheets.com 7) 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.

1) 2)
95
150
3)
5)
93
141
4)
6)
150
~~ 150 ~~
86
7) ~~ 150 ~~
94

212

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

| 1.
2.
3.
4.
5.
6. | | Answers | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1-6 | 83 | 67 | | 50 | 33 | 17 | 0 | Math Modified [www.CommonCoreSheets.com](www.CommonCoreSheets.com) 7

FAQs

How do you classify a triangle as acute, obtuse, or right?

A triangle is acute if all angles are less than 90°, obtuse if one angle is greater than 90°, and right if one angle is 90°.

How do you determine whether a triangle is equilateral, isosceles, or scalene?

Equilateral means three equal sides and three equal angles; isosceles means two equal sides and two equal angles; scalene means no equal sides and no equal angles.

What information does the answer key provide?

The answer key gives the combined codes for each item, specifying both the angle type (A/O/R) and the side type (E/I/S) for triangles labeled 1 through 8 (and another set for 1 through 6).

Sep 30, 2026

Uploaded by Fans