Law of Sines Calculator

Solve triangles using Law of Sines. Free online law of sines calculator.

The Law of Sines Calculator solves triangles using the relationship a/sin(A) = b/sin(B) = c/sin(C). Enter known sides and angles to find the missing values. This powerful tool handles AAS, ASA, and SSA (ambiguous case) triangle problems for comprehensive triangle solving.

Common use cases

  • Surveying and navigation
  • Astronomy calculations
  • Physics applications
  • Engineering design
  • Trigonometry coursework

How to use

  1. Enter a known side and its opposite angle
  2. Enter another side OR angle
  3. Click calculate for missing values
  4. Check for ambiguous case (SSA)
  5. View all triangle measurements

FAQ

What is the Law of Sines?

a/sin(A) = b/sin(B) = c/sin(C), relating sides and opposite angles in any triangle.

What is the ambiguous case?

In SSA (two sides and non-included angle), there may be 0, 1, or 2 valid triangles.

When should I use Law of Sines?

Use when you know an angle and its opposite side, plus one more angle or side.

When should I use Law of Cosines instead?

Use Law of Cosines for SAS (two sides and included angle) or SSS (three sides).