Segment Addition Postulate Calculator

Use AB + BC = AC to find a missing segment length.

AC (whole) 13

Formula: AC = AB + BC

Step-by-step with your numbers:

1. Values used:

2. AB = 5

3. BC = 8

5. AC (whole) = AB + BC = 5 + 8 = 13

Did we solve your problem today?

When B lies between A and C, the two parts add up to the whole segment.

The math behind it

The Segment Addition Postulate states AB + BC = AC whenever point B is on segment AC.

AB = 5 and BC = 8 → AC = 13.

How do I find a missing part?

Subtract: if you know AC and AB, then BC = AC − AB.