🔺 Triangle Calculator
Enter any 2 values (sides a, b, or hypotenuse c).
What is the Triangle Calculator?
The Triangle Calculator solves for every missing property of a triangle — angles, sides, area, perimeter, and triangle type — from whatever three values you already know. It offers three modes: three sides (SSS, using Heron's formula and the law of cosines), two sides plus the included angle (SAS), and a dedicated right-triangle solver using the Pythagorean theorem.
How to Use It
Pick the tab that matches what you know. For SSS, enter all three side lengths. For SAS, enter two sides and the angle between them. For a right triangle, enter any two of the three values (two legs, or one leg and the hypotenuse) and leave the third blank. Click Calculate to get the full set of missing values.
When to Use It
Use it for geometry and trigonometry homework, when laying out a triangular piece of land, roof, or garden bed and you need the area or a missing side, or when checking whether three given lengths can even form a valid triangle before building or cutting material to those dimensions.
Who Benefits
Students working through trigonometry problems, surveyors and carpenters calculating angles and areas on the job, DIYers planning a triangular deck or roof section, and teachers demonstrating the law of cosines, Heron's formula, or the Pythagorean theorem all get instant, accurate results without manual formula work.