Grade 5 Math · Spatial Sense

Classify triangles

Classify a triangle by its side lengths (scalene, isosceles, equilateral) or by its angle measures (acute, right, obtuse). Unlimited questions, five difficulty levels, and a full worked solution every time, included free with weekly lessons.

Practice this skill Curriculum: G5-E1.1

Try one

A triangle has angles measuring 90 deg, 55 deg, 35 deg. How would you classify it by its angles?

  • cannot be determined
  • right
  • acute
  • obtuse

Answer: right

See one solved, step by step

A triangle has angles measuring 9 deg, 145 deg, 26 deg. How would you classify it by its angles?

  • right
  • cannot be determined
  • acute
  • obtuse
📘 Worked solution
19 + 145 + 26 = 180The three angles of any triangle always add up to 180 degrees.
2Classification: obtuseOne angle is more than 90 deg, so it's an obtuse triangle.

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