Can three lengths make a triangle?

Grade 8 Math Worksheet

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Circle the best answer, or write your answer on the line.

  1. Esme has three paper strips: 2.6 cm, 7.5 cm and 4.9 cm. Can they make a triangle?

    • Yes: any three paper strips make a triangle
    • Yes: 7.5 + 2.6 = 10.1 cm, longer than 4.9 cm
    • Yes: 2.6 + 4.9 is not shorter than 7.5 cm
    • No: 2.6 + 4.9 = 7.5 cm exactly, so they lie flat
  2. Jun has three crayons: 5.8 cm, 9.5 cm and 3.7 cm. Can they make a triangle?

    • No: 3.7 + 5.8 = 9.5 cm exactly, so they lie flat
    • Yes: 3.7 + 5.8 is not shorter than 9.5 cm
    • Yes: any three crayons make a triangle
    • Yes: 9.5 + 3.7 = 13.2 cm, longer than 5.8 cm
  3. Milo has two pieces of yarn, 2.7 cm and 6.2 cm, for two sides of a triangle. The third side is more than ? cm and less than ? cm. Type both numbers, smaller first.

  4. Noah has two paper strips, 4.6 cm and 9.5 cm, for two sides of a triangle. The third side is more than ? cm and less than ? cm. Type both numbers, smaller first.

  5. Pia has two paper strips, 2.5 cm and 10 cm, for two sides of a triangle. The third side is more than ? cm and less than ? cm. Type both numbers, smaller first.

  6. Ren has 4.5 cm and 7.2 cm paper strips for two sides of a triangle. Which length can the third side be?

    • 12.4 cm
    • 6.3 cm
    • 11.7 cm
    • 2.1 cm
  7. Tala has 3.6 cm and 8.4 cm pieces of yarn for two sides of a triangle. Which length can the third side be?

    • 12.5 cm
    • 4.8 cm
    • 10.5 cm
    • 3.9 cm
  8. Ari has paper strips of 3.4 cm and 6.9 cm for two sides of a triangle. The third side is a whole number of cm. What is the longest it can be?

  9. Bo has pieces of yarn of 5.6 cm and 8.7 cm for two sides of a triangle. The third side is a whole number of cm. What is the longest it can be?

  10. Esme has paper strips of 2.2 cm and 9.5 cm for two sides of a triangle. The third side is a whole number of cm. What is the longest it can be?

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Can three lengths make a triangle?

Answer Key - Grade 8 Math Worksheet

Circle the best answer, or write your answer on the line.

  1. Esme has three paper strips: 2.6 cm, 7.5 cm and 4.9 cm. Can they make a triangle?

    • Yes: any three paper strips make a triangle
    • Yes: 7.5 + 2.6 = 10.1 cm, longer than 4.9 cm
    • Yes: 2.6 + 4.9 is not shorter than 7.5 cm
    • No: 2.6 + 4.9 = 7.5 cm exactly, so they lie flat
  2. Jun has three crayons: 5.8 cm, 9.5 cm and 3.7 cm. Can they make a triangle?

    • No: 3.7 + 5.8 = 9.5 cm exactly, so they lie flat
    • Yes: 3.7 + 5.8 is not shorter than 9.5 cm
    • Yes: any three crayons make a triangle
    • Yes: 9.5 + 3.7 = 13.2 cm, longer than 5.8 cm
  3. Milo has two pieces of yarn, 2.7 cm and 6.2 cm, for two sides of a triangle. The third side is more than ? cm and less than ? cm. Type both numbers, smaller first.

    3.5, 8.9
  4. Noah has two paper strips, 4.6 cm and 9.5 cm, for two sides of a triangle. The third side is more than ? cm and less than ? cm. Type both numbers, smaller first.

    4.9, 14.1
  5. Pia has two paper strips, 2.5 cm and 10 cm, for two sides of a triangle. The third side is more than ? cm and less than ? cm. Type both numbers, smaller first.

    7.5, 12.5
  6. Ren has 4.5 cm and 7.2 cm paper strips for two sides of a triangle. Which length can the third side be?

    • 12.4 cm
    • 6.3 cm
    • 11.7 cm
    • 2.1 cm
  7. Tala has 3.6 cm and 8.4 cm pieces of yarn for two sides of a triangle. Which length can the third side be?

    • 12.5 cm
    • 4.8 cm
    • 10.5 cm
    • 3.9 cm
  8. Ari has paper strips of 3.4 cm and 6.9 cm for two sides of a triangle. The third side is a whole number of cm. What is the longest it can be?

    10
  9. Bo has pieces of yarn of 5.6 cm and 8.7 cm for two sides of a triangle. The third side is a whole number of cm. What is the longest it can be?

    14
  10. Esme has paper strips of 2.2 cm and 9.5 cm for two sides of a triangle. The third side is a whole number of cm. What is the longest it can be?

    11