Triangle Calculator

Calculate triangle area, perimeter, angles, and missing sides using various methods and formulas

Triangle Calculator

Three Sides (SSS)

Results

Enter triangle measurements to see calculations.

Triangle Properties

• Sum of angles = 180°
• Largest angle opposite longest side
• Triangle inequality: a + b > c
• Area = ½ × base × height
• Perimeter = a + b + c

Understanding Triangles

Triangle Types

Triangles are classified by sides (equilateral, isosceles, scalene) and by angles (acute, right, obtuse). Each type has unique properties.

Area Formulas

Various formulas exist: base×height/2, Heron's formula for three sides, and SAS formula using two sides and included angle.

Law of Cosines

c² = a² + b² - 2ab cos(C). Used to find unknown sides or angles when you know two sides and included angle.

Law of Sines

a/sin(A) = b/sin(B) = c/sin(C). Useful for solving triangles when you know two angles and one side.

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