What Is a Triangle Calculator?
A triangle calculator solves geometric properties of a triangle given three sides. It computes the area (Heron's formula), perimeter, and all three interior angles in degrees using the Law of Cosines.
Triangle Calculator
Triangle Calculator
Triangle GeometryRight Triangle (90°)
Area
6.0000
Perimeter
12.0000
Angle A / B
36.87° / 53.13°
Angle C
90.00°
Frequently Asked Questions
How do you calculate the area of a right triangle?
The area of a right triangle is computed as Area = (base × height) / 2.
What is the Pythagorean theorem?
The Pythagorean theorem states that in a right-angled triangle, the square of the hypotenuse (c) is equal to the sum of the squares of the other two sides (a² + b² = c²).
What is the sum of angles in any triangle?
The interior angles of any planar triangle always sum up to exactly 180 degrees (or π radians).
What inputs are needed to solve a triangle?
You need at least three known values, including at least one side length (e.g. Side-Side-Side, Side-Angle-Side, or Angle-Side-Angle).
Related Calculators
Basic Calculator
This is a free online basic calculator with memory functions that handles everyday arithmetic — addition, subtraction, multiplication, and division.
MathScientific Calculator
Free online scientific calculator with trigonometry, logarithms, powers, roots, factorials, and DEG/RAD modes. Supports full keyboard input and expression history.
MathFraction Calculator
Free online fraction calculator. Add, subtract, multiply, and divide fractions and mixed numbers with step-by-step simplifying.
MathPercentage Calculator
Free online percentage calculator. Calculate percentage increase, decrease, percentage of numbers, and fraction conversions instantly.
MathGPA Calculator
This is a free online GPA calculator that computes your Grade Point Average from courses and credit hours using a 4.0 or custom grading scale.
EverydayFeatures & Highlights
- Area & Perimeter Solver
- All 3 Angles via Law of Cosines