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Math Grade 6-8

Angle Relationships: Complementary and Supplementary

Finding missing angles that add to 90 degrees or 180 degrees

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Practice identifying complementary and supplementary angles and finding missing angle measures.

Read each problem carefully. Use the definitions of complementary and supplementary angles to find each answer. Show your work in the space provided.

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Finding missing angles that add to 90 degrees or 180 degrees

Math - Grade 6-8

Instructions: Read each problem carefully. Use the definitions of complementary and supplementary angles to find each answer. Show your work in the space provided.
  1. 1
    A right angle divided into a small acute angle and a larger acute angle.

    Two angles are complementary. One angle measures 35 degrees. What is the measure of the other angle?

  2. 2
    A straight angle divided into one larger angle and one smaller angle.

    Two angles are supplementary. One angle measures 112 degrees. What is the measure of the other angle?

  3. 3
    A right angle split into a small angle and its complementary angle.

    Angles A and B are complementary. Angle A measures 27 degrees. Write and solve an equation to find the measure of angle B.

  4. 4
    A straight angle split into an acute angle and its supplementary angle.

    Angles C and D are supplementary. Angle C measures 49 degrees. Write and solve an equation to find the measure of angle D.

  5. 5
    An acute angle compared with its smaller complement and larger supplement.

    An angle measures 64 degrees. Is its complement or its supplement larger? Find both angle measures and explain.

  6. 6
    A right angle divided into two equal angles.

    An angle and its complement have equal measures. What is the measure of each angle?

  7. 7
    A straight angle divided into two equal angles.

    An angle and its supplement have equal measures. What is the measure of each angle?

  8. 8
    Two adjacent angles forming a straight line.

    Two angles form a straight line. One angle measures 73 degrees. What is the measure of the other angle, and what relationship do the angles have?

  9. 9
    A right angle split into two angles where one is about twice the other.

    The measure of an angle is x degrees. Its complement measures 2x degrees. Find the value of x and the measure of each angle.

  10. 10
    A straight angle split into two unequal supplementary angles.

    The measure of an angle is x degrees. Its supplement measures x + 40 degrees. Find the value of x and the measure of each angle.

  11. 11
    Two acute angles that fit together to form a right angle.

    Decide whether angles measuring 38 degrees and 52 degrees are complementary, supplementary, or neither. Explain your answer.

  12. 12
    Two angles that fit together to form a straight angle.

    Decide whether angles measuring 95 degrees and 85 degrees are complementary, supplementary, or neither. Explain your answer.

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