# The Law of Sines

### The Law of Sines

The Law of Sines is the relationship between sides and angles in any triangle.

### Introduction

Let's prove the theorem.

(Hints)

**MENU1**...If *a sinB* = *b sinA*, you can make a triangle.

**MENU2**...If a triangle exists, always *a sinB* = *b sinA*.

**MENU3**...Let R be the radius of the circumscribed circle of triangle ABC, then *2RsinC = **c**.
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Drag the red point