# Law of Sines Proof

- Author:
- lori.white

- Topic:
- Sine

## Triangle ABC

Using Right Triangle Trigonometry, prove the Law of Sines:
Refer to Triangle ABC above .

Begin by looking at the right triangle ACD. Find the length of f using a right triangle relationship for Sine.

Now look at right triangle CDB. Find the length of f using a right triangle relationship for Sine.

If f has 2 different measurements what can we say about them?

Set the two answers for f equal to each other and rewrite to prove the first part of the the Law of Sines.