This Grade 4 challenge worksheet asks students to find missing angles and classify triangles by both angle and side. Multiple choice and fill-in-the-blank questions use the 180 degree rule, including problems where students decide if a triangle is even possible. Hints guide subtraction steps and remind students that two right angles cannot fit in one triangle. This Grade 4 worksheet supports classroom practice and homework review at home.
Style:
Classifying Triangles
Part A: Multiple Choice
Circle the best answer for each question.
1. A triangle has angles of 60 and 70 degrees. What is the third angle?
A) 30 degrees
B) 40 degrees
C) 50 degrees
D) 60 degrees
2. Which set of angles could form a triangle?
A) 80, 60, 50 degrees
B) 100, 50, 40 degrees
C) 60, 60, 60 degrees
D) 90, 90, 10 degrees
3. A triangle has angles of 90, 45, and 45 degrees. How would you classify it?
A) Right scalene
B) Acute equilateral
C) Right isosceles
D) Obtuse isosceles
4. A triangle has sides 6 cm, 6 cm, and 6 cm. Which classification is always correct?
A) Right equilateral
B) Acute equilateral
C) Obtuse scalene
D) Right isosceles
Part B: Fill in the Blank
Write the correct answer on each line.
1. A triangle has angles 35 and 95 degrees. The third angle is 50 degrees.
2. A triangle with angles 30, 60, and 90 degrees is a right scalene triangle by sides.
3. A triangle has angles 20, 20, and 140 degrees, making it an obtuse isosceles triangle.
4. If a triangle has two 50 degree angles, the third angle is 80 degrees.
5. A triangle cannot have two 90 degree angles, because the three angles must add to 180 degrees.
Classifying Triangles
★ Part A: Multiple Choice
Circle the best answer for each question.
1. A triangle has angles of 60 and 70 degrees. What is the third angle?
A) 30 degrees
B) 40 degrees
C) 50 degrees
D) 60 degrees
2. Which set of angles could form a triangle?
A) 80, 60, 50 degrees
B) 100, 50, 40 degrees
C) 60, 60, 60 degrees
D) 90, 90, 10 degrees
3. A triangle has angles of 90, 45, and 45 degrees. How would you classify it?
A) Right scalene
B) Acute equilateral
C) Right isosceles
D) Obtuse isosceles
4. A triangle has sides 6 cm, 6 cm, and 6 cm. Which classification is always correct?
A) Right equilateral
B) Acute equilateral
C) Obtuse scalene
D) Right isosceles
★ Part B: Fill in the Blank
Write the correct answer on each line.
1) A triangle has angles 35 and 95 degrees. The third angle is 50 degrees.
2) A triangle with angles 30, 60, and 90 degrees is a right scalene triangle by sides.
3) A triangle has angles 20, 20, and 140 degrees, making it an obtuse isosceles triangle.
4) If a triangle has two 50 degree angles, the third angle is 80 degrees.
5) A triangle cannot have two 90 degree angles, because the three angles must add to 180 degrees.
Ready to Practice?
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9 Questions
12-18 minutes
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