What are Supplementary Angles? | How to Find Missing Supplementary Angles | Math with Mr. J

[Music] welcome to math with mr j [Music] in this video i'm going to cover supplementary angles now supplementary angles are two angles that add up to 180 degrees and a 180 degree angle is going to make a straight line so if the sum of two angles is 180 degrees they are supplementary let's jump into our examples where we have supplementary angles but one of the angles will be unknown or missing and we need to find that missing angle measure for number one we have a given angle measure of 65 degrees so angle d b c equals 65 degrees so we need to find the missing or unknown angle we are going to look for angle a b d now we know that the sum of these two angles is going to be 180 degrees they are supplementary angles so we need to think we have 65 degrees and then we need to add what to get to 180 degrees if you can figure these out mentally that works for sure but if not that's fine too so what we can do we can take the sum of these two angles which we know is going to be 180 degrees so we will write 180 degrees and we'll subtract the angle measure that we are given 65 degrees that's going to give us our missing angle so let's subtract 0 minus 5 well we need to borrow 10 minus 5 is 5 7 minus 6 is 1 and then we have a 1 in the hundreds place so 115 degrees and that is angle a b d 105 degrees we can always double check our work and make sure that that angle measure is correct and we do this by adding 115 degrees plus the 65 degrees and make sure they equal 180 we'll start with 5 plus 5 which is 10 we'll put our 0 here carry the one one plus one is two plus six is eight and then we have a one in the hundreds place so 180 degrees 115 degrees was correct and we are good to go let's move on to number two where we have a given angle measure of 124 degrees so that's for angle t s u so with that given angle we need to find the angle measure of angle r s u let's calculate what that missing or unknown angle measure is by taking 180 degrees and subtracting our given angle measure of 124 degrees so we'll start with zero minus four we need to borrow so we have 10 minus 4 which is 6 7 minus 2 is 5 and then 1 minus 1 is 0 so we have 56 degrees angle rsu equals 56 degrees and again we can always double check let's do that so we can add 124 degrees plus 56 degrees and make sure that equals 180 degrees four plus six gives us ten carry the one one plus two is three plus five eight and then we have a 1 in the hundreds place so 180 degrees 56 degrees was correct for angle rsu so there you have it there's an explanation of supplementary angles and how to find a missing or unknown supplementary angle i hope that helped thanks so much for watching until next time peace