Triangle Calculator
Choose input method, enter values, then Calculate. Returns area, perimeter and angles when possible.
Triangle Calculator: Calculate Triangle Properties Online Easily
Introduction
A Triangle Calculator is a powerful online tool that helps you quickly find different properties of a triangle, such as area, perimeter, angles, side lengths, and height. Instead of doing manual geometry formulas, you can enter the known values, and the calculator will instantly solve for the missing properties.
This tool is useful for students learning trigonometry, teachers preparing lessons, architects, engineers, and anyone working with triangular shapes in real-world projects. With a Triangle Calculator online, you can save time, reduce errors, and get accurate results instantly.
Formula / Working
The calculator applies different mathematical formulas depending on the type of triangle and the information you provide. Here are the most common ones:
1. Perimeter of a Triangle
P=a+b+cP = a + b + cP=a+b+c
where a, b, c are the sides of the triangle.
2. Area of a Triangle (Heron’s Formula):
A=s(s−a)(s−b)(s−c)A = \sqrt{s(s-a)(s-b)(s-c)}A=s(s−a)(s−b)(s−c)
where s = \frac{a+b+c}{2} \] (semi-perimeter). ### 3. **Area of a Triangle (Base × Height):** \[ A = \tfrac{1}{2} \times b \times h
4. Using Trigonometry (Sine Rule):
A=12absin(C)A = \tfrac{1}{2} ab \sin(C)A=21absin(C)
5. Pythagoras’ Theorem (Right Triangles):
c2=a2+b2c^2 = a^2 + b^2c2=a2+b2
where c is the hypotenuse.
The calculator automatically selects the right formula based on the input (sides, angles, or height).
Step-by-Step Usage
Using the Triangle Calculator online is very simple:
- Open the calculator in your browser.
- Select the type of calculation you want (area, perimeter, angles, etc.).
- Enter the known values (sides, base, height, or angles).
- Click the Calculate button.
- Instantly view the triangle’s properties on screen.
Examples
Example 1: Area Using Base and Height
Base = 8 cm, Height = 5 cm A=12×8×5=20 cm2A = \tfrac{1}{2} \times 8 \times 5 = 20 \, cm^2A=21×8×5=20cm2
✅ The calculator will show 20 cm².
Example 2: Perimeter of a Triangle
Sides: a = 6 cm, b = 7 cm, c = 5 cm P=6+7+5=18 cmP = 6 + 7 + 5 = 18 \, cmP=6+7+5=18cm
✅ The calculator will show 18 cm.
Example 3: Area Using Heron’s Formula
Sides: a = 7 cm, b = 9 cm, c = 12 cm s=7+9+122=14s = \tfrac{7+9+12}{2} = 14s=27+9+12=14 A=14(14−7)(14−9)(14−12)=14×7×5×2=980≈31.3 cm2A = \sqrt{14(14-7)(14-9)(14-12)} = \sqrt{14 \times 7 \times 5 \times 2} = \sqrt{980} \approx 31.3 \, cm^2A=14(14−7)(14−9)(14−12)=14×7×5×2=980≈31.3cm2
✅ The calculator will show 31.3 cm².
FAQs
Q1. What is a triangle calculator?
It is an online tool that calculates different triangle properties such as area, perimeter, sides, and angles based on the given values.
Q2. Which types of triangles can I calculate?
You can calculate properties for scalene, isosceles, equilateral, and right-angled triangles.
Q3. Do I need to know formulas?
No, the calculator applies the right formula automatically—you only need to enter the known values.
Q4. Can I calculate angles with this tool?
Yes, many triangle calculators use trigonometric formulas to calculate missing angles.
Q5. Is the triangle calculator free to use?
Yes, most online triangle calculators are free, simple, and accessible on all devices.