Law of Sines Calculator | Free Online Triangle Calculator

Law of Sines Calculator

Calculate unknown sides and angles in any triangle using the law of sines formula.

c a b A B C

Understanding the Law of Sines

The law of sines is a fundamental relationship in trigonometry that connects the sides and angles of any triangle. It states that the ratio of the sine of an angle to the length of the opposite side is constant for all three angles and sides of a triangle.

Formula

For any triangle with sides a, b, c and angles A, B, C:

a/sin(A) = b/sin(B) = c/sin(C)

When to Use

Use the law of sines when you have:

  • Two angles and any side (AAS or ASA)
  • Two sides and an angle opposite to one of them (SSA)