Triangle Calculator
Solve a triangle from three sides or two sides plus the included angle.
Instructions: Triangle Calculator
Follow these steps to get a reliable result without unnecessary setup.
- 1
Choose SSS when you know all three sides, or SAS when you know two sides and their included angle.
- 2
Choose the options in Triangle Calculator that match your intended output, such as units, format, mode, range or quality when those controls are available.
- 3
Run Triangle Calculator and review the displayed result, preview or validation message before proceeding.
- 4
Check the entered units, dates, decimal placement and any assumptions before relying on the result.
- 5
Use the available reset, copy or download action in Triangle Calculator when you are satisfied with the result; only actions supported by this tool are shown.
About this tool: Triangle Calculator
Calculate missing sides, angles, area and perimeter using Heron’s formula and the laws of sines/cosines, with impossible-triangle validation.
Use it to compare scenarios quickly while keeping the relevant values, units, dates or rates visible on one page.
Triangle Calculator is presented in the shared NexterHub tool layout so the working controls stay near the top while the method, example, limitations and related utilities remain available below the result.
How it works
SSS uses the law of cosines for angles and Heron’s formula for area; SAS finds the third side with the law of cosines.
Practical example
Sides 3, 4 and 5 form a right triangle with area 6.
Important notes
Check the entered units, dates, decimal placement and any assumptions before relying on the result.
Privacy & processing
The calculation is performed in the browser from the values you enter.
Frequently asked questions
What does Triangle Calculator do?
Solve a triangle from three sides or two sides plus the included angle.
How do I use Triangle Calculator?
Start with the main input step: Choose SSS when you know all three sides, or SAS when you know two sides and their included angle. Then choose any relevant options, run the tool and review the result.
How does Triangle Calculator calculate or process the result?
SSS uses the law of cosines for angles and Heron’s formula for area; SAS finds the third side with the law of cosines.
What should I check before using a result from Triangle Calculator?
Check the entered units, dates, decimal placement and any assumptions before relying on the result.
Does Triangle Calculator send my input to a NexterHub server?
The calculation is performed in the browser from the values you enter.
Can I use Triangle Calculator on a phone or tablet?
Yes. Triangle Calculator uses the responsive NexterHub tool layout, so controls and results adapt to smaller touch screens.