Law of Sines

Calculate the angles in a generic triangle using the Law of Sines

Law of Sines

The "Law of Sines" can be used to calculate the angles of a triangle.

The Law of Sines states that the ratio of the length of a side of a triangle to the sine of the angle opposite that side is constant for all three sides and angles.

Variables:

  • a, b, c = length of sides in triangle (m, ft ...)
  • A, B, C = angles in the triangle (degrees)
Calculator

Inputs

Results

Angle B-- degrees
Angle C-- degrees
ParameterValueUnitDescription
Side ainputs.side_amLength of side a
Side binputs.side_bmLength of side b
Side cinputs.side_cmLength of side c
Angle Ainputs.angle_AdegreesAngle A of the triangle
Angle BASIN(inputs.side_b * SIN(RADIANS(inputs.angle_A)) / inputs.side_a) * 180 / PI()degreesCalculated angle B
Angle C180 - inputs.angle_A - ASIN(inputs.side_b * SIN(RADIANS(inputs.angle_A)) / inputs.side_a) * 180 / PI()degreesCalculated angle C