Triangle Calculator

Calculate triangle area, perimeter, and angles using various measurement inputs.

Calculate triangle area, perimeter, angles, and other properties using various input combinations. This comprehensive triangle calculator works with side lengths, angles, height, and base measurements to solve any triangle problem.

Calculation Method

Side A (length)

Side B (length)

Side C (length)

Side A (length)

Angle C (degrees)

Side B (length)

Angle A (degrees)

Side A (length)

Angle B (degrees)

Angle A (degrees)

Angle B (degrees)

Side A (length)

Hypotenuse (length)

Side A (length)

Base (length)

Height (length)

Side A (length)

Side B (length)

Area

Unit

How to Use This Triangle Calculator

This comprehensive calculator can solve triangles using various input methods:

SSS (Side-Side-Side): Enter all three side lengths
SAS (Side-Angle-Side): Enter two sides and the included angle
ASA (Angle-Side-Angle): Enter two angles and the included side
AAS (Angle-Angle-Side): Enter two angles and any side
RHS (Right-Hypotenuse-Side): For right triangles with hypotenuse and one side
Base and Height: Calculate area when you know base and height
Two Sides and Area: Find the angle between two known sides

Triangle Properties Calculated

The calculator provides complete triangle information including:

All three side lengths
All three interior angles
Area using multiple formulas
Perimeter and semi-perimeter
Height to each side
Triangle classification (acute, right, obtuse)

Triangle Formulas Used

Area Formulas:

Heron's Formula: √(s(s-a)(s-b)(s-c)) where s = semi-perimeter
Base × Height ÷ 2
½ab sin(C) for two sides and included angle

Law of Cosines: c² = a² + b² - 2ab cos(C)

Law of Sines: a/sin(A) = b/sin(B) = c/sin(C)

Note: For a valid triangle, the sum of any two sides must be greater than the third side, and the sum of all angles must equal 180°. The calculator will validate inputs and provide error messages for invalid triangles.