Calculation Results
Triangle Diagram
Formula Used
Step-by-Step Calculation
Unit Conversions
| Unit | Perimeter | Area |
|---|
Merged Result Data
Calculation History
| Date | Mode | Type | Perimeter | Area | Unit |
|---|---|---|---|---|---|
| No saved calculations. | |||||
Formula Used
How to Use
Select the triangle calculation mode first. Enter every required value using one consistent length unit. Choose the required output precision before calculating.
Review the validity message and triangle classification. Check formulas, substitutions, angles, and converted measurements. Use the diagram to confirm the entered shape.
Copy results or download CSV and PDF reports. Saved history remains inside your browser. Clear it whenever stored calculations are unnecessary.
Example Data
| Mode | Inputs | Expected result |
|---|---|---|
| SSS | a = 3, b = 4, c = 5 | Perimeter 12; area 6 |
| Base and height | b = 10, h = 6 | Area 30 |
| SAS | a = 8, b = 10, C = 60° | Area about 34.641 |
| Equilateral | a = 9 | Perimeter 27; area about 35.074 |
| Coordinates | A(0,0), B(6,0), C(2,5) | Area 15 |
Frequently Asked Questions
How is a triangle perimeter calculated?
Add all three side lengths. The units remain linear. Every side must use the same unit.
How is triangle area calculated from base and height?
Multiply the base by perpendicular height. Divide that product by two. The result uses square units.
When should Heron’s formula be used?
Use it when all three sides are known. First calculate the semiperimeter. Then apply the square-root expression.
Can invalid sides form a triangle?
No side may equal or exceed the other two combined. This is the triangle inequality. Invalid inputs produce an error.
Can the calculator find missing sides?
Yes, selected modes find missing sides. SAS uses the cosine rule. Right triangles use the Pythagorean theorem.
How are triangle angles calculated?
The calculator uses inverse cosine relationships. All three sides must be available. Their angles should total 180 degrees.
What is a degenerate triangle?
Its points lie on one straight line. Its area equals zero. It is not a valid ordinary triangle.
Can coordinates calculate area?
Yes, the shoelace formula calculates coordinate area. Distance formulas calculate side lengths. Collinear points are rejected.
What is the difference between perimeter and area?
Perimeter measures the outer boundary length. Area measures the enclosed surface. Their units are therefore different.