Coding

Simplest way to remember Complementary vs Supplementary Angles!

  • 00:00:00 hi guys this is Keith galley and today
  • 00:00:02 we are going to go over a very simple
  • 00:00:05 way to remember the difference between
  • 00:00:07 complementary and supplementary angles
  • 00:00:13 we'll begin with complementary angles
  • 00:00:16 complementary angles are two angles that
  • 00:00:19 add up to 90 degrees so then the graph
  • 00:00:22 here down below if we had a first angle
  • 00:00:24 of that say 30 degrees
  • 00:00:27 well it's complement would be what you
  • 00:00:31 need to add to it to get 90 so it would
  • 00:00:33 be 60 degrees and there's a really neat
  • 00:00:38 trick that you can use to remember that
  • 00:00:40 so you see up here at the top I have
  • 00:00:42 complementary written well one way to
  • 00:00:45 remember it is you just draw a little
  • 00:00:47 line right through here and if you kind
  • 00:00:50 of look at this on the top the
  • 00:00:53 complementary actually looks like a 90
  • 00:00:56 so if you just draw a line through that
  • 00:00:58 see you pretty much have a 90 degree
  • 00:01:02 thing right there and that's how you can
  • 00:01:04 remember that a complementary angle adds
  • 00:01:06 to 90 degrees next let's move on to
  • 00:01:11 supplementary angles supplementary
  • 00:01:14 angles are two angles that add up to be
  • 00:01:16 180 degrees so in this graph here down
  • 00:01:20 below if we had a first angle of 50
  • 00:01:24 degrees its supplementary angle would be
  • 00:01:30 130 degrees similar to the last example
  • 00:01:36 we can also do a little trick here with
  • 00:01:38 the supplementary angle to remember that
  • 00:01:40 it's 180 so if we connect the two ends
  • 00:01:43 of this s we get an 8 if we connect the
  • 00:01:47 top of this u we can get a little 0 I
  • 00:01:50 see as 80 right there and then finally
  • 00:01:54 just remember that we have a 90 degree
  • 00:01:57 complement and then a 180 degree
  • 00:02:02 supplement so supplementary angle this
  • 00:02:05 is a little bit of a more of a stretch
  • 00:02:07 than the complementary angle but you can
  • 00:02:09 kind of make a little bit of a 180 out
  • 00:02:11 of the supplementary angle
  • 00:02:12 remember that that 130 and 50 are
  • 00:02:16 supplements because they add up to 180
  • 00:02:20 one final example I want to just bring
  • 00:02:23 up quickly is that you might see in an
  • 00:02:26 assignment if you're in algebra you
  • 00:02:28 might see an angle of let's say X right
  • 00:02:33 here well this doesn't change anything
  • 00:02:35 X's supplement still adds up to 180 so
  • 00:02:39 if that angle was X this would be 180
  • 00:02:45 minus X because if you fly add together
  • 00:02:49 180 minus X plus X you still are just
  • 00:02:53 left with 180 and this can apply to any
  • 00:02:57 sort of value that's here for this angle
  • 00:03:00 so maybe we had like 2x plus 5 or
  • 00:03:03 something it would still just be 180
  • 00:03:04 minus 2x plus 5 because those added
  • 00:03:08 together make 180 so the key thing to
  • 00:03:10 remember is supplementary angles add up
  • 00:03:13 to 180
  • 00:03:16 thank you for watching this video