Giải thích các bước giải:
\(\begin{array}{l}
\frac{{bz - cy}}{a} = \frac{{cx - az}}{b} = \frac{{ay - bx}}{c}\\
\Rightarrow \frac{{bxz - cxy}}{{ax}} = \frac{{cxy - ayz}}{{by}} = \frac{{ayz - bxz}}{{cz}} = \frac{{bxz - cxy + cxy - ayz + ayz - bxz}}{{ax + by + cz}} = 0\\
\Rightarrow bxz - cxy = cxy - ayz = ayz - bxz = 0\\
\Rightarrow \frac{x}{a} = \frac{y}{b} = \frac{z}{c}
\end{array}\) (đpcm)
