Segment Addition Postulate Calculator
Solve AB + BC = AC for the missing segment.
Enter your values
Choose one of: AC (whole), AB, BC.
Enter the ab you are working with.
Enter the bc you are working with.
Enter the ac you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Solved AC
- 12
- AB
- 7
- BC
- 5
- AC
- 12
- Check
- AB + BC = AC ✓
Working
- 17 + 5 = 12
Quick answer
The segment addition postulate says that if B is between A and C, then AB + BC = AC.
AB + BC = AC
At a glance
| What it does | Solve AB + BC = AC for the missing segment. |
|---|---|
| Category | Math |
| Inputs needed | Solve for, AB, BC, AC |
| Main output | Solved AC |
| Formula | AB + BC = AC |
| Cost | Free — no sign-up, no download |
How to use the Segment Addition Postulate Calculator
- 1Choose which segment is unknown.
- 2Type the two lengths you know.
- 3Read the missing length and the consistency check.
Inputs explained
- Solve for
- Choose one of: AC (whole), AB, BC.
- AB
- Enter the ab you are working with.
- BC
- Enter the bc you are working with.
- AC
- Enter the ac you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Solve forAC (whole)
- AB7
- BC5
- AC12
Results
- Solved AC12
- AB7
- BC5
- AC12
- CheckAB + BC = AC ✓
- 7 + 5 = 12
Frequently asked questions
What is the segment addition postulate?
If point B lies on segment AC between A and C, the two shorter pieces add to the whole: AB + BC = AC.
Can AB be longer than AC?
No — the whole segment AC is always the largest, so a negative result means the labels are swapped.
What do I need to enter into the Segment Addition Postulate Calculator?
Just 4 values: solve for, ab, bc, ac. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Segment Addition Postulate Calculator work out the answer?
The segment addition postulate says that if B is between A and C, then AB + BC = AC. It applies the formula AB + BC = AC and shows the working so you can check each step by hand.
Is the Segment Addition Postulate Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.