# Video: Subtracting Two Side Lengths to Find the Missing Side Length

Find the length of line segment 𝐴𝐵.

01:35

### Video Transcript

Find the length of line segment 𝐴𝐵.

We know that the distance from 𝐴 to 𝐶 equals 11.1 meters. We also know that distance from 𝐵 to 𝐶 is 8.2 meters. The value we’re missing is the distance from 𝐴 to 𝐵. Here’s what we know: from 𝐴 to 𝐶 equals line 𝐴𝐵 plus line 𝐵𝐶. The total distance from 𝐴 to 𝐶 is 11.1 meters. And that is equal to our missing value plus 8.2.

To find the missing value, we need to find the difference. We need to subtract 8.2 meters from the total distance 11.1 meters. If we start all the way on the right, we realize that we can’t subtract two from one. We borrow from our ones place, bring over a one. And now, we can say 11 minus two equals nine tenths, bring down the decimal. In the whole numbers, we now have 10 minus eight. 10 minus eight equals two. The difference is 2.9 meters.

And that tells us the length of line segment 𝐴𝐵 is 2.9 meters.