Triangle Calculator
Calculate area, perimeter, sides, and angles for any triangle. Solves using SSS, SAS, or simply Base and Height formulas.
Diagram is for reference (sides a, b, c opposite to angles A, B, C).
Triangle Formulas Used
1. Area of a Triangle
The simplest formula when you know base and height is:
Area = ½ × base × height
When you know three sides (SSS), we use Heron's Formula:
s = (a + b + c) / 2
Area = √(s(s-a)(s-b)(s-c))
2. Law of Cosines
This law relates the lengths of sides to the cosine of one of its angles. It is used to solve SSS and SAS triangles.
c² = a² + b² - 2ab cos(C)
3. Perimeter
The perimeter is simply the sum of all three sides:P = a + b + c
? Frequently Asked Questions
These are acronyms for the information you have about the triangle. SSS (Side-Side-Side) means you know all three side lengths. SAS (Side-Angle-Side) means you know two sides and the angle between them.
No. According to the Triangle Inequality Theorem, the sum of any two sides must be greater than the third side. If a+b ≤ c, the sides won't connect.
For a right triangle, the two legs act as the base and height. You can use the basic 'Base & Height' mode or our specific Pythagorean Theorem Calculator.