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Triangle Classification Worksheet

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Triangle Classification Worksheet

Classify triangles by their angles and side lengths. Show your working where needed.

Classifying by angles

1.Triangle P has angles of 48°, 62° and 70°. Classify it by its angles.

2.Triangle Q has angles of 90°, 35° and 55°. Classify it by its angles.

3.Triangle R has angles of 112°, 34° and 34°. Classify it by its angles.

4.Which statement describes an acute triangle?

Each angle is smaller than 90°
Exactly one angle is 90°
One angle is larger than 90°
All three angles are equal to 90°

5.True or false: A triangle with one angle greater than 90° is obtuse.

TrueFalse

Classifying by side lengths

6.A triangle has side lengths 8 cm, 8 cm and 8 cm. Name its side classification and state each angle size.

7.A triangle has side lengths 7 cm, 7 cm and 10 cm. Classify it by its sides. What are the two equal angles called?

8.A triangle has side lengths 5 cm, 6 cm and 9 cm. Classify it by its sides.

9.Match each side classification to its defining property.

Equilateral
Isosceles
Scalene
Base angles

Exactly two equal sides
Three equal sides
Three sides of different lengths
The equal angles opposite the equal sides of an isosceles triangle

10.An isosceles triangle has a vertex angle of 74°. Calculate the size of each base angle.

Use both classifications

11.At a building site, Arjun checks a triangular brace with side lengths 6 cm, 8 cm and 10 cm and angles 90°, 37° and 53°. Classify it by its angles and by its sides.

12.Explain why a triangle cannot contain two right angles. Use the fact that the interior angles of a triangle add to 180°.

13.Draw one acute scalene triangle and one right isosceles triangle. Mark any right angle and use matching tick marks to show equal sides.

Draw and label the triangle here.