Thursday, May 3, 2012

More ways to remember complementary and supplementary

You probably already have 50 ways to remember the difference between complementary and supplementary. Here's one more that I made up and I think it's pretty cool. I recognize that it's very possible (although unlikely) that someone else also make up this trick somewhere in the universe. Let's just hope that I came up with it first.

I always tell my students to take the co in complementary, and simply draw a line on the c so that it becomes 90. Therefore, complementary angles add up to 90 degrees. Supplementary doesn't work as well, but I like it anyway. Take the su, draw a 1 next to the s, put a slash through the s to make it look like an 8, and top off the u to make it look like a zero. Voila! 180

Nathan Kraft


  1. Hey, Nathan. James Key here (Sandy Spring, MD). Here is a mnemonic I came up with:

    C = corner/complementary
    S = straight line/supplementary

    Useful for learning which is which, but have to make sure they don't assume that the angles share a vertex once they learn it!

    1. C comes before S
      90 comes before 180

  2. P.S. Keep rockin' constantly!

  3. P.P.S. I hate homework too! But I still assign it and "check it" every day. Wish there were a way to change the system so they get the benefit without me having to spend (waste?) class time looking at it/checking it off on my chart/posting it in the gradebook.

  4. Very cool way to get your kids to remember the difference. I'll send you a picture tomorrow of my word wall poster. You'll get a kick out of it!

  5. Whatever happened to just remembering C comes before S, and 90 comes before 180? :) What picture did Stades share with you that he can't share with meeee??

  6. one of my students made up this one: C looks like the top half of an S so a Complementary angle is half a Supplementary angle

  7. i like all of these mnemonics

  8. I created this one, good relationships complement each others looks creating a 90 degree angle, amazing relationships supplement or help each other to become better people creating 180 degrees.

  9. As in to complement is ok but to supplement is better! 90 is ok 180 is better or wider.