Triangle Calculator
Calculate triangle properties from sides, angles, height, or area. Get all measurements, see a visual representation, and learn about triangle theory!
Choose Calculation Method
Triangle Types, Properties, and Formulas
- Scalene: All sides and angles are different.
- Isosceles: Two sides are equal and so are their opposite angles.
- Equilateral: All sides and angles are equal (each angle = 60°).
- Right: One angle is 90°; Pythagorean Theorem applies.
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Area Formulae:
- From sides a, b, c: Area = √[s(s-a)(s-b)(s-c)] (Heron's Formula), where s = (a+b+c)/2
- From base and height: Area = (base × height) / 2
- With sides and angle: Area = (ab sin C)/2 or equivalents
- Law of Sines: a/sin A = b/sin B = c/sin C
- Law of Cosines: c² = a² + b² - 2ab cos C
Triangle Calculator – Solve Any Triangle Instantly with Angles, Sides & Area
Geometry just got easier. Whether you’re solving a triangle in trigonometry class, estimating roof angles, or working on a CAD project, our Triangle Calculator is the fastest way to compute sides, angles, perimeter, and area of any triangle—be it right, acute, obtuse, equilateral, or scalene.
🧠 What Is a Triangle Calculator?
A Triangle Calculator is an online tool that helps you:
- 🔺 Solve for missing sides and angles
- 📐 Compute the area, perimeter, or height
- 🔄 Use known values like SSS, SAS, ASA, AAS, or right triangle rules
- 🧮 Apply trigonometric formulas like the sine rule, cosine rule, or Pythagoras’ theorem
It’s perfect for students, architects, engineers, designers, and DIYers.
📐 Triangle Types Supported (Triangle Calculator)
| Triangle Type | Description | Visual Traits |
|---|---|---|
| Right Triangle | Has one 90° angle | Used in trigonometry |
| Equilateral | All sides and angles are equal | All 60° angles |
| Isosceles | Two sides and two angles are equal | Symmetrical triangle |
| Scalene | All sides and angles are different | No symmetry |
| Acute | All angles less than 90° | Pointy triangle |
| Obtuse | One angle greater than 90° | Flattened triangle |
🧮 How the Triangle Calculator Works
You can solve a triangle by entering any of the following combinations:
- SSS (three sides)
- SAS (two sides + included angle)
- ASA (two angles + included side)
- AAS (two angles + non-included side)
- Right triangle with any side or angle
The tool will instantly calculate:
- 📐 Missing angles
- 📏 Missing side lengths
- 📦 Area and 🔄 perimeter
- 🧱 Height (altitude) of the triangle
🔢 Example Calculation
Given:
- Side a = 5 cm
- Side b = 6 cm
- Angle C = 45°
Using the Law of Cosines:
c² = a² + b² – 2ab × cos(C)
c² = 25 + 36 – 60 × cos(45°)
c² ≈ 61 – 42.43 = 18.57
c ≈ √18.57 = 4.31 cm
The calculator would then find remaining angles and the area instantly.
🧰 Features of the Triangle Calculator
- ✅ Works for any triangle configuration
- 🧮 Supports trigonometric laws: sine, cosine, tangent
- 📐 Handles radians or degrees
- 🔁 Recalculates when you modify any variable
- 📊 Real-time updates with visual preview
- 📱 Mobile and desktop-friendly
🧑🏫 Who Uses This Calculator?
- 🎓 High school and college students studying geometry
- 👨🔧 Engineers needing triangle measurements
- 👷 Architects designing roof angles or structural supports
- 🧰 DIYers cutting plywood, tile, or framing
- 🎯 Anyone working with angles, heights, or slope geometry
🔥 Features Included
- Triangle calculator
- Solve triangle online
- Triangle angle calculator
- Triangle area and perimeter calculator
- Law of sines calculator
- Law of cosines calculator
- Pythagorean theorem calculator
- Right triangle solver
- Triangle height and base calculator
🧭 Related Tools on Desmos Calculators
- Pythagorean Theorem Calculator – for solving right triangles fast
- Angle Calculator – measure or find missing angles
- Area Calculator – calculate area of various 2D shapes
🔗 Trusted External Resources
✅ Final Thoughts
Whether you’re prepping for exams or cutting materials in the garage, the Triangle Calculator is a game-changer. It eliminates the guesswork from geometry and delivers fast, accurate, and visual solutions for any type of triangle.