I'll solve this worksheet by classifying each triangle based on its angles as acute, obtuse, or right.
Let me first recall the definitions:
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Acute triangle: All three angles are less than 90°.
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Obtuse triangle: One angle is greater than 90°.
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Right triangle: One angle is exactly 90° (often marked with a square symbol).
Now I'll examine each triangle one by one:
Triangle 1: Has angles of 35°, 55°, and a right angle (90°, indicated by the square symbol). Since it has one 90° angle, this is a
right triangle.
Triangle 2: Has angles of 109°, 54°, and 34°. Since 109° > 90°, this is an
obtuse triangle.
Triangle 3: Has angles of 75°, 52°, and 53°. All angles are less than 90°, so this is an
acute triangle.
Triangle 4: Has angles of 84°, 49°, and 97°. Since 97° > 90°, this is an
obtuse triangle.
Triangle 5: Has angles of 80°, 50°, and 50°. All angles are less than 90°, so this is an
acute triangle.
Triangle 6: Has angles of 26°, 64°, and a right angle (90°, indicated by the square symbol). Since it has one 90° angle, this is a
right triangle.
Triangle 7: Has angles of 40°, 50°, and a right angle (90°, indicated by the square symbol). Since it has one 90° angle, this is a
right triangle.
Triangle 8: Has angles of 38°, 67°, and 55°. All angles are less than 90°, so this is an
acute triangle.
Triangle 9: Has angles of 15°, 135°, and 30°. Since 135° > 90°, this is an
obtuse triangle.
The final classification for each triangle is:
1) Right
2) Obtuse
3) Acute
4) Obtuse
5) Acute
6) Right
7) Right
8) Acute
9) Obtuse
Parent Tip: Review the logic above to help your child master the concept of identify triangles worksheet.
