Subtract angles in degrees minutes seconds 2
Subtract angles in degrees minutes seconds 2


>>This is YourMathGal, Julie Harland. Please visit my website at yourmathagal.com where all of my videos are organized by topic. This is part 2 of subtracting angles that are given in degrees, in minutes, and seconds, and we’re going to do these two problems on this video. So here’s the first problem, you might want to start by writing the 26 degrees minus 102 degrees 38 minutes. And a common mistake is for somebody to say,”Oh, that’s 24 degrees 38 minutes. That’s wrong because 126 degrees minus 102 degrees is 24 minutes but you also have to subtract 38 degrees from that. So, it would be smaller, not bigger than 24 degrees. So, first of all, make sure you don’t do that. You have to subtract 38 from something and right now, there’s no degrees up here, if you want write 0. And so you can’t take 38 from 0, when you can, you’d had a negative number that complicates things. So instead, remember that 1 degree equals 60 minutes, so we could borrow from this 126 and make it 125 degrees and so we have 1 degree to write as 60 seconds. All right, so now we can do our subtraction because we could take 38 from 60 and 102 from 125 so that would give us just 23 degrees and 22 minutes. [ Pause ] All right, here’s our next one. So again, we want to start off by writing 87 degrees and notice this 12 seconds, so notice I don’t have anything in for the minutes here so I’m going to write 0 minutes for now and 12 seconds. And I’m going to subtract 14 degrees 8 minutes and 50 seconds. So we’re gong to have to do some borrowing here. So first of all, I noticed I’ve got 12 seconds, we can’t do 12 minus 50 so usually we go over and try to take from minutes but notice there aren’t 20 minutes. So I got to go all the way over here to the 87 degrees and I’m going to borrow, you know, that’s the same as 86 degrees plus one more degree which I am now going to write as 60 minutes. Okay, so you see that my first step is to rewrite the 87 degrees as 86 degrees and 60 minutes. But, I still have this problem, I solved 12 degrees minus 50, I’m sorry, 12 seconds minus 50 seconds. I need to borrow now from the 60 minutes. So I’m going to write that as 59 minutes and I get to add 60 seconds, right? Because– so I’m going to use a different color and leave this down a little, so we’re all– plenty of room. Okay, so I have 60 minutes, I’m going to write that as 59 minutes plus 60 seconds. So I got to add 60 seconds over here, right, could you do that in your head? 60 plus 12 is 72 seconds. If you need to write over– you could always write all this stuff over on the side work. Right now, it’s possible to subtract and yeah it is kind of confusing. So if you don’t get it the first time, try and try again. 86 minus 14, right, that’s 72 degrees, 59 minus 8 is 51 degrees, I’m sorry, 51 minutes, and 72 minus 50 is 22 seconds. So you may wonder, “Oh I wonder of that’s right.” Well, the one way you could always check any subtraction problem is to do an addition problems. So, here’s how you could check. Just add these together, add the 72 degrees and I did a video at first on adding, so you can go back and look at that 51 minutes 22 seconds, you’re going to add 14 degrees 8 minutes 50 seconds. And when you first add, you’re going to get this 86 degrees, 59 minutes, and 72 seconds. But you could rewrite the 72 seconds, watch, a little shortcut here. That’s really going to be 1 minute and 12 seconds left over, right? We needed that 1 so it’s right under there. So, are you with me? I’m writing 72 minutes as 1 degree 12 seconds, so that gives me 86 degrees 60 minutes and 12 seconds, but now I could do it again. This 60 minutes could be written as 1 degree, right? So I really have 86 degrees and 12 minutes. I’m sorry, 87 degrees, I forgot to add the 1. And now you look, that was what I started out with, right, 87 degrees 12 minutes. So it does check out. So you could always do that with your checking any of your subtraction problems, go back and add. This is YourMathgal, Julie Harland. Please visit my website at yourmathagal.com where all of my videos are organized by topic.

Leave a Reply

Your email address will not be published. Required fields are marked *