Testinar Grade 4 math

Angle Measure as Additive

Students will decompose angles and use addition or subtraction equations to find unknown angle measures.

CH07-09 Measurement, Data, and Angles
Name
Date
Score
____ / 8
Directions Solve each problem. Show your reasoning on the page or on separate paper. Check the answer key only after finishing.

  1. An angle is split into two smaller angles. One measures 30° and the other measures 45°. What is the measure of the whole angle?

    1. 15°
    2. 65°
    3. 75°
    4. 90°

  2. Two rays form an angle with a measure of 80°. If one part of the angle is 32°, what is the measure of the other part?

    1. 48°
    2. 50°
    3. 112°
    4. 35°

  3. A straight angle measures 180°. If it is split into two angles, and one angle is 125°, what is the measure of the other angle?

    1. 55°
    2. 65°
    3. 305°
    4. 180°

  4. An angle measures 120° and is divided into three equal parts. What is the measure of each part?

    1. 30°
    2. 40°
    3. 60°
    4. 120°

  5. Look at the angle diagram. Two angles share a vertex. One angle measures 28° and the other measures 47°. Together, what is the total measure of both angles?

    Angle Measure as Additive visual for G4-C07-T09-Q005
    1. 19°
    2. 75°
    3. 104°
    4. 90°

  6. A right angle measures 90°. If it is divided into two angles measuring 35° and another angle, what is the measure of the unknown angle?

    1. 45°
    2. 55°
    3. 125°
    4. 35°

  7. A pie is cut into slices. One slice represents an angle of 40° and another slice represents an angle of 60°. If these two slices are placed together, what angle do they form?

    1. 20°
    2. 60°
    3. 100°
    4. 200°

  8. Two smaller angles are combined to form a larger angle. The smaller angles measure 22° and 58°. What is the measure of the larger angle?

    1. 80°
    2. 36°
    3. 58°
    4. 90°
Teacher and parent reference

Answer key and explanations

  1. C. 75°

    When you split an angle into smaller parts, add them to find the whole: \(30°+45°=\mathbf{75°}\).

  2. A. 48°

    To find the missing part, subtract what you know from the total: \(80° - 32° = \mathbf{48°}\).

  3. A. 55°

    Since a straight angle measures 180°, subtract the known part: \(180° - 125° = \mathbf{55°}\).

  4. B. 40°

    Split the angle equally among all parts: \(120° \div 3 = \mathbf{40°}\).

  5. B. 75°

    The diagram shows two angles meeting at one vertex. Add them together: \(28° + 47° = \mathbf{75°}\).

  6. B. 55°

    A right angle is 90°. Subtract the known part: \(90° - 35° = \mathbf{55°}\).

  7. C. 100°

    When pie slices are combined, their angles add up: \(40° + 60° = \mathbf{100°}\).

  8. A. 80°

    When smaller angles combine, they add to form the larger angle: \(22° + 58° = \mathbf{80°}\).

Free Testinar sample Reviewed November 6, 2026 testinar.com
Page UP