Triangle Calculator
The Triangle Calculator is a free online geometry tool that helps you calculate triangle area, perimeter, missing sides, and angles using different combinations of known values — such as 3 sides (SSS), 2 sides & included angle (SAS), or 2 angles & included side (ASA). Whether you’re a student, teacher, engineer, or architect, this calculator simplifies triangle formulas and gives instant, accurate results.
What Is a Triangle Calculator?
A Triangle Calculator is a digital math tool that solves any triangle based on partial data. It uses geometric laws like the Law of Sines, Law of Cosines, and Heron’s Formula to compute unknown angles, sides, and the triangle’s area.
You just need to enter known values (like sides or angles), and within a second, you’ll get:
- All missing side lengths
- Internal angle measures
- Perimeter of the triangle
- Area (square units)
This makes it perfect for school geometry homework, trigonometry practice, and even real-world applications like construction, design, or physics.
How to Use the Online Triangle Calculator
Using this calculator is simple and intuitive:
Step 1: Select the Known Values
Choose one of the following options from the dropdown:
- SSS (3 sides): when you know all three sides
- SAS (2 sides & included angle): when you know two sides and the angle between them
- ASA (2 angles & included side): when you know two angles and one included side
Step 2: Enter Your Values
Input the sides (x, y, z) and/or angles (A, B, C) in the provided boxes. The calculator automatically adjusts the form depending on your selection.
Step 3: Click “Calculate”
Once you press the Calculate button, the results appear instantly below — showing area, perimeter, sides, and all angles with proper decimal precision.
Step 4: Review the Results
If you make an error (like impossible triangle values), the calculator highlights the issue with an easy-to-read error message.
Formulas Used in the Triangle Calculator
Types of Triangle Calculations Supported
| Calculation Type | Known Inputs | Output Results |
|---|---|---|
| SSS | 3 Sides | 3 Angles, Area, Perimeter |
| SAS | 2 Sides + Included Angle | 3rd Side, Remaining Angles, Area, Perimeter |
| ASA | 2 Angles + Included Side | 3rd Angle, Remaining Sides, Area, Perimeter |
Why Use This Triangle Calculator?
- ✅ Instant Results
- Get your area, angles, and sides in real-time without manual calculations.
- ✅ Supports All Combinations (SSS, SAS, ASA)
- Handles any possible triangle configuration automatically.
- ✅ Accurate to 4 Decimal Places
- Ensures precision for both academic and professional geometry calculations.
- ✅ Mobile & Desktop Friendly
- Built using responsive CSS, the tool adapts beautifully to all devices.
- ✅ Error Validation
- If you input impossible triangle values (like violating the triangle inequality rule), the tool alerts you immediately.
Example: Calculate Triangle with 3 Sides (SSS)
- Given:
x = 6, y = 7, z = 8 - Step 1: Compute semi-perimeter
s = (6 + 7 + 8) / 2 = 10.5 - Step 2: Apply Heron’s Formula
Area = √[10.5(10.5−6)(10.5−7)(10.5−8)] = 20.333 square units - Step 3: Use the Law of Cosines to find angles
A = 46.57°, B = 59.04°, C = 74.39° - Output:
- Area = 20.333
- Perimeter = 21
- Angles = A (46.57°), B (59.04°), C (74.39°)
Benefits of Online Triangle Solvers
- Saves Time: No need for manual trigonometric calculations.
- Reduces Errors: Automated formulas guarantee accuracy.
- Learning Aid: Great for understanding geometry visually.
- Cross-Platform: Works on Android, iPhone, tablets, and desktops.
- Visual Diagram: Highlights the triangle sides and angles interactively.
FAQ – Triangle Calculator
- Q1. Can I find the area of a triangle with only 3 sides?
Yes, using Heron’s formula, the calculator finds the area directly from all three side lengths. - Q2. Can this calculator solve for missing angles?
Yes, it calculates all three angles automatically using the law of cosines or sines. - Q3. Does it work for obtuse or right triangles?
Absolutely. The formula applies to all triangle types — acute, right, or obtuse. - Q4. Is this tool accurate for professional use?
Yes, it uses double-precision floating math accurate to 4 decimal points. - Q5. Is it mobile responsive?
Yes, the layout auto-adapts to smartphones, tablets, and desktop screens.
Conclusion
The Triangle Calculator is one of the most useful geometry tools online — combining visual representation, mathematical accuracy, and simplicity. With support for SSS, SAS, and ASA, it can instantly compute missing sides, angles, area, and perimeter of any triangle in seconds. Whether you’re working on homework, architecture, or engineering, this calculator saves time, improves understanding, and delivers results that are both precise and reliable.
Search Keywords
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