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Worksheet

Types of Triangles

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Show your work for each problem.

  1. 1.
    A triangle has all three sides measuring 7 cm. What type of triangle is this?
    1. a)Scalene
    2. b)Right
    3. c)Isosceles
    4. d)Equilateral
  2. 2.
    A triangle has angles measuring 40°40°, 60°60°, and 80°80°. What type of triangle is this by angles?
    1. a)Acute
    2. b)Equilateral
    3. c)Obtuse
    4. d)Right
  3. 3.
    Which triangle type has exactly one angle equal to 90°90°?
    1. a)Acute triangle
    2. b)Obtuse triangle
    3. c)Equilateral triangle
    4. d)Right triangle
  4. 4.
    A triangle has sides of 5 cm, 5 cm, and 8 cm, with angles of about 37°37°, 37°37°, and 106°106°. What is its complete classification?
    1. a)Obtuse isosceles
    2. b)Acute isosceles
    3. c)Right isosceles
    4. d)Obtuse scalene
  5. 5.
    A triangle has angles of 60°60°, 60°60°, and 60°60°. What type is it by sides?
    1. a)Cannot determine
    2. b)Equilateral
    3. c)Isosceles
    4. d)Scalene
  6. 6.
    A triangle has sides of 3 cm, 4 cm, and 5 cm. What type of triangle is it by its sides?
    1. a)Cannot be determined
    2. b)Isosceles
    3. c)Equilateral
    4. d)Scalene
  7. 7.
    A triangle has angles of 35°35°, 55°55°, and 90°90°. What type is it by angles?
    1. a)Obtuse
    2. b)Not a valid triangle
    3. c)Right
    4. d)Acute
  8. 8.
    A triangle has angles of 70°70° and 50°50°. What is the third angle in degrees? (Enter just the number)
  9. 9.
    A triangle has angles of 30°30° and 120°120°. What is the third angle in degrees?
  10. 10.
    An isosceles triangle has one angle of 40°40°, and it is NOT one of the two equal angles. How many degrees is each of the two equal angles?
  11. 11.
    Classify the triangle with sides 8 cm, 8 cm, and 8 cm.
  12. 12.
    Classify the triangle with angles 50°50°, 60°60°, and 70°70°.
  13. 13.
    Find the third angle and classify a triangle with angles 45°45° and 90°90°.
  14. 14.
    A triangle has sides 6 cm, 6 cm, and 10 cm. Classify it by sides and explain why.
  15. 15.
    A triangle has angles 25°25° and 130°130°. Find the third angle and classify it by angles.
  16. 16.
    Classify a triangle with sides 5 cm, 12 cm, 13 cm and angles 23°23°, 67°67°, 90°90° by its sides and by its angles.
  17. 17.
    An isosceles triangle has a vertex angle of 100°100°. Find the base angles and give the complete classification.
  18. 18.
    Can a triangle have angles 50°50°, 60°60°, and 80°80°? Verify and classify it if valid.
Interactive lesson with step-by-step solutions and more practice (free): mathorio.com/en/learn/geometry/triangles/types-of-triangles
Today's challengeOne problem, three tries