Complementary and Supplementary Angles

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*.

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*

C C C C How can I remember that? Draw the C in Complementary 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

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

Click on the link below to manipulate different angles that are Supplementary. http://www.mathopenref.com/anglecomplementary.html

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*.

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*

S S S 1S0* How can I remember that? Draw the S in Supplementary 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*

Click on the link below to manipulate different angles that are Supplementary. http://www.mathopenref.com/anglesupplementary.html