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Math Grade 4-5

Angles and Triangles

Classifying angles and identifying triangle types

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Practice recognizing acute, right, and obtuse angles and classifying triangles by their sides and angles.

Read each problem carefully. Use what you know about angles and triangles to answer each question. Show your work when needed.

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Classifying angles and identifying triangle types

Math - Grade 4-5

Instructions: Read each problem carefully. Use what you know about angles and triangles to answer each question. Show your work when needed.
  1. 1
    A small acute angle with a curved arc showing its opening.

    An angle measures 35 degrees. Is it acute, right, or obtuse?

  2. 2
    A right angle with a square corner marker.

    An angle measures 90 degrees. Is it acute, right, or obtuse?

  3. 3
    A wide obtuse angle with a curved arc showing its opening.

    An angle measures 120 degrees. Is it acute, right, or obtuse?

  4. 4
    An example of an acute angle.

    Draw one acute angle and label it with a measure that makes sense.

  5. 5
    An example of a right angle.

    Draw one right angle and label it with its measure.

  6. 6
    An example of an obtuse angle.

    Draw one obtuse angle and label it with a measure that makes sense.

  7. 7
    A triangle with three equal sides marked the same.

    A triangle has 3 equal sides. What kind of triangle is it by its sides?

  8. 8
    A triangle with two equal sides marked the same.

    A triangle has 2 equal sides and 1 side that is a different length. What kind of triangle is it by its sides?

  9. 9
    A triangle with three different side lengths.

    A triangle has 3 sides of different lengths. What kind of triangle is it by its sides?

  10. 10
    A triangle with one right angle marked.

    A triangle has one right angle. What kind of triangle is it by its angles?

  11. 11
    A triangle with three acute angles marked.

    A triangle has three acute angles. What kind of triangle is it by its angles?

  12. 12
    A triangle with one obtuse angle marked.

    A triangle has one obtuse angle. What kind of triangle is it by its angles?

  13. 13
    Two right angles on a base with parallel sides that do not meet to form a triangle.

    Can a triangle have two right angles? Explain why or why not.

  14. 14
    Two obtuse angles on a base with sides spreading apart instead of meeting.

    Can a triangle have two obtuse angles? Explain why or why not.

  15. 15
    A triangle with two equal sides and a longer base.

    A triangle has side lengths 5 cm, 5 cm, and 8 cm. Classify the triangle by its sides.

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