I have an equillateral triangle and require to calculate the lengths of two parallel lengths.

I have included a sketch to help identify.

BC=AB=AC

YZ AY AZ

I know;

AB = 3

AC = 3

AY = 2

AZ = 2

I require to find the ratios BC and YZ

AB=AC=BC

AZ AY YZ

3=3=x

2 2 x

How do I work with this method above to isolate BC and YZ