🔺 Triangle Perimeter Calculator
Calculate triangle perimeter from three sides
Triangle Perimeter Formula
Add all three sides together
Triangle Types
Equilateral Triangle
All three sides equal. Perimeter = 3 × side
Example: sides 5, 5, 5 → Perimeter = 15
Isosceles Triangle
Two sides equal. Perimeter = 2a + b
Example: sides 5, 5, 7 → Perimeter = 17
Scalene Triangle
All sides different. Perimeter = a + b + c
Example: sides 3, 4, 5 → Perimeter = 12
Triangle Inequality Theorem
Rule:
The sum of any two sides must be greater than the third side.
a + b > c
b + c > a
a + c > b
✅ Valid: 3, 4, 5 (3+4=7 > 5, 4+5=9 > 3, 3+5=8 > 4)
❌ Invalid: 2, 3, 10 (2+3=5 < 10)
Common Triangle Perimeters
Real-World Applications
🏗️ Construction
- • Fencing triangular areas
- • Roof truss edges
- • Frame construction
- • Material estimates
🌳 Landscaping
- • Garden bed borders
- • Path edging
- • Triangular planters
- • Hedge trimming
🎨 Art & Design
- • Frame borders
- • Pattern design
- • Quilting
- • Geometric art
📐 Mathematics
- • Geometry problems
- • Trigonometry
- • Engineering calculations
- • Architecture
How to Use This Calculator
Enter Your Values
Input the required values in the calculator fields above. Make sure all inputs are valid numbers.
Click Calculate
Press the "Calculate" button to perform the calculation and see your results.
Review Results
Review the calculated results displayed below. Use these values for your needs.
About Triangle Perimeter Calculator
The Triangle Perimeter Calculator is a useful tool for calculating triangle perimeter values. This calculator helps you quickly and accurately determine the results you need for your calculations.
When to Use This Calculator
- Quick Calculations: Get instant results without manual computation
- Accuracy: Ensure precise calculations every time
- Planning: Use for project planning and estimation
- Verification: Double-check your manual calculations
Why Use Our Calculator?
- ✅ Instant Results: Get accurate calculations immediately
- ✅ Easy to Use: Simple interface for all skill levels
- ✅ 100% Free: No registration or payment required
- ✅ Mobile Friendly: Works on all devices
- ✅ Accurate: Precise mathematical calculations
Tips for Best Results
- Double-Check Inputs: Verify all values before calculating
- Use Valid Numbers: Ensure inputs are valid numbers
- Review Results: Check results for reasonableness
- Clear and Retry: Clear inputs if you need to recalculate
Frequently Asked Questions
How do you find the perimeter of a triangle?
Simply add all three side lengths: P = a + b + c. Example: sides 3, 4, 5 → 3 + 4 + 5 = 12 units.
What is the triangle inequality theorem?
The sum of any two sides must be greater than the third side. Otherwise, the sides cannot form a triangle. Example: 2, 3, 10 fails because 2+3=5 < 10.
What is semiperimeter?
Half of the perimeter. s = P/2. Used in Heron's formula to calculate triangle area: Area = √[s(s-a)(s-b)(s-c)].
Can I find perimeter if I only know two sides?
No, you need all three sides to calculate perimeter. However, for right triangles, if you know two sides, you can use Pythagorean theorem to find the third.
What's the perimeter of an equilateral triangle?
P = 3 × side. Since all sides are equal, just multiply one side by 3. Example: side = 5 → P = 3 × 5 = 15 units.