Use AB + BC = AC to solve for the missing segment length.
Last updated: June 2026 | By Patchworkr Team
Enter AB and BC as real numbers.
If point B lies between A and C, then the lengths satisfy AB + BC = AC.
The relationship only applies when the three points are collinear and B is between A and C.
1. Choose which segment you want to solve for.
2. Enter the two known lengths.
3. Read the live result and confirm the segment addition relationship.
If AB = 7 and BC = 5, then AC = 12.
AB + BC = AC -> 7 + 5 = 12
The calculator should show 12 when solving for AC.
Yes, as long as the other two are known.
Yes. The point B must lie between A and C.
No. Segment lengths should be non-negative.
Then the postulate does not apply.
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