Triangle Calculator

Solve triangles by entering sides and angles. Supports SSS, SAS, ASA, AAS modes with area, perimeter, and SVG diagram.

Known Values

Side a

Side b

Side c

Enter all values above to solve the triangle.

Key Formulae

Law of Cosines c² = a² + b² − 2ab·cos(C)

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

Heron's Formula Area = √(s(s−a)(s−b)(s−c)), s = (a+b+c)/2

SAS Area Area = 0.5 × a × b × sin(C)

1

Choose a solving mode

Select SSS, SAS, ASA, AAS, or Right Triangle from the tabs.
2

Enter known values

Fill in the required sides and/or angles for your chosen mode.
3

View the solution

All sides, angles, area, and perimeter are calculated. The SVG diagram updates live.

What do SSS, SAS, ASA, AAS mean?

SSS = three sides known. SAS = two sides + included angle. ASA = two angles + included side. AAS = two angles + non-included side.

How is the area calculated?

Using Heron's formula (from three sides) or the SAS formula (0.5 x a x b x sin(C)).

What if the triangle is impossible?

The tool checks the triangle inequality theorem and displays an error if the values cannot form a valid triangle.

Is my data sent anywhere?

No. All calculations run in your browser.

Enter known sides and angles to solve any triangle completely. Choose

from SSS (three sides), SAS (two sides + included angle), ASA (two

angles + included side), AAS (two angles + non-included side), or

right-triangle mode. Get all sides, angles, area, and perimeter.

Detects triangle type (equilateral, isosceles, scalene, right, acute,

obtuse). An SVG diagram updates live. Step-by-step solution shown.

All processing runs in your browser.

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