## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$A=30$, $B=75$, $C=75$ and $x=8$.
Since the triangles are similar, then the angles are equal. That is $A=30$, $B=75$, $C=75$. To find $x$, we set up a ratio between corresponding sides: $$\frac{x}{16}=\frac{6}{12}=\frac{1}{2}\Longrightarrow x=\frac{16}{2}=8 .$$