Classifying triangles worksheets
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A triangle gets its name from its angles or its sides. A square mark means a right angle, and matching ticks mean equal sides.
Two grades, each its own sheet. Print one here, or open a grade for examples and teaching notes.
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4th grade Core grade
Each print is a different sheet with its own answer key. You don't need to sign up.
Classifying triangles worksheets for fourth grade show one drawn triangle per problem with three names to circle: acute, right, or obtuse. Right angles carry a small square mark, and the deciding question is always how the biggest angle compares to a square corner.
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5th grade
Fifth grade alternates the two naming systems: half the problems classify by angles (acute, right, obtuse) and half by sides (equilateral, isosceles, scalene). One triangle can hold a name from each family, like a right isosceles triangle.
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