Complementary and Supplementary Angles

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Complementary and Supplementary Angles
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Complementary Angles

• Two angles are complementary if the sum of their
  angles equals 90.
• If one angle is known, its complementary angle
  can be found by subtracting the measure of its
  angle from 90.

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Example of Complementary Angles

• What is the complementary angle of 43?
• SOLUTION 90 - 43 47
• So, 43 and 47 are complementary angles
• Angle A measures 25 and Angle B measures 65.
  Angle A and Angle B are complementary angles
  because together they create a 90 angle.
• JUSTIFICATION 25 65 90

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How can I remember that?

• Draw the C in Complementary
• C
• Since complementary angles equal 90, turn that C
  into a number 9 by drawing a line, then add a 0
  after that to make it 90.
• So you change the C in complementary into 90!!
• C C C

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Another way to remember

• Just remember this phrase
• It is always RIGHT to give COMPLIMENTS
• A RIGHT angle is 90 and COMPLIMENT and
  COMPLEMENTARY sound alike

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http//www.mathopenref.com/anglecomplementary.html

• Click on the link below to manipulate different
  angles that are Supplementary.

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Supplementary Angles

• Two angles are supplementary if the sum of their
  angles equals 180.
• If one angle is known, its supplementary angle
  can be found by subtracting the measure of its
  angle from 180.

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Example of Supplementary Angles

• What is the supplementary angle of 143?
• SOLUTION 180 - 143 37
• Angle A measures 120 and Angle B measures 60.
  Angle A and Angle B are complementary angles
  because together they create a 180 angle.
• JUSTIFICATION 120 60 180

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How can I remember that?

• Draw the S in Supplementary
• S
• Since supplementary angles equal 180, turn that
  S into a number 8 by drawing a line diagonal,
  then add a 1 in front of that and a 0 after to
  make it 180.
• So you change the S in supplementary into 180!!
• S S 1S0

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http//www.mathopenref.com/anglesupplementary.htm
l

• Click on the link below to manipulate different
  angles that are Supplementary.