• Solve Triangle

    Solving a triangle means finding unknowns of any of its sides or angles using a combination of 3 rules. The three rules are the Sine rule, the Cosine rule and the Sum of the three angles. For these rules to work, some conditions must be satisfied. These conditions are:
    1 - The sum of any two sides must not equal to or be less than the third side.
    2 - At least one side must be known, to know the size of the triangle

    Types of Triangles


    AAS: Angle, Angle, Side. The side is NOT between the angles.


    ASA: Angle, Side, Angle. The side is between the angles.


    SAS: Side, Angle, Side. The angle is between the sides.


    SSA: Side, Side, Angle. The angle is NOT between the sides.


    SSS: Side, Side, Side. All angles are unknown.

Solve Triangle Tool

Use this tool to solve any of the triangles shown under types of triangles. From the triangle shown in Fig 1 below, each side has an opposite angle with the same letter label in upper case, the three rules mentioned above are:

1- The Sine rule states that: a/sin(A) = b/sin(B) = c/sin(C).
2- The Cosine rule states that, for a side such as a: a2 = b2 + c2 - 2bc * Cos(A). Similar rules apply to the other two sides.
3- The Sum of the three angles = 180. All types of triangles are shown to the right.

Solve triangle

Select a triangle type, then fill in the missing angles and/or sides in the data boxes appearing below:


Fig 1

 Select triangle type: