Law of Sines Proof
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.