Law of Sines
Solve a triangle using the Law of Sines: find missing sides and angles.
Formula
a/sin(A) = b/sin(B) = c/sin(C)
Each side divided by the sine of its opposite angle is constant. Use this ratio to find unknown sides and angles.
Examples
a=7, A=40°, B=60°
a=10, A=30°, B=45°
a=5, A=90°, B=30°
Frequently Asked Questions
When do I use the Law of Sines?
Use it when you know at least one side and its opposite angle, plus one more piece of information (AAS, ASA, or SSA).
What is the Law of Sines formula?
a/sin(A) = b/sin(B) = c/sin(C).
About this Calculator
Solve a triangle using the Law of Sines: find missing sides and angles. All calculations are performed in your browser for instant results. Formulas are mathematically exact using JavaScript's built-in Math functions.