Law of Cosines Calculator

Your details

Length of the first known side.
Length of the second known side.
The angle between sides a and b, opposite the side you are solving for.
°
ResultObtuse triangle
6.6663
Side c6.6663
Angle A46.2375°
Angle B96.7625°
Angle C37°
Perimeter25.6663
Semi-perimeter (s)12.8332
Area26.4799
Inradius (r)2.0634
Circumradius (R)5.5385
Triangle typeObtuse triangle
Angle A46.23748662435536
Angle B96.76251337564464
Angle C37

Side c is 6.6663, completing a obtuse triangle.

  • With two sides and the included angle (SAS), the third side is uniquely determined. The calculator has also solved all three angles and the full set of triangle properties.
  • The area is 26.4799, found using Heron's formula once all three sides are known.
  • The inradius is the radius of the largest circle that fits inside the triangle; the circumradius is the radius of the circle that passes through all three vertices.

Next stepSwitch to angle mode and enter all three sides to verify every angle, or use the law of sines as a cross-check: a/sin(A) = b/sin(B) = c/sin(C).

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