Given $A(0,a),B(-b,0),C(c,0)$ On $BC$, the point $K(\lambda,0)$; on $AB$, the point $M(\mu,\frac{a\mu}{b}+a)$. Condition $\Rightarrow \mu=\frac{b(b-c+2\lambda}{c-\lambda}$. The line $MK\ :\ y=\frac{a(\frac{\mu}{b}+1)}{\mu-\lambda} \cdot (x-\lambda)$ or $y=\frac{a(x-\lambda)}{b-c-\lambda}$ or $a(x-\lambda)-(b-c-\lambda)y=0$. We solve the system $\left\{\begin{array}{ll} ax-(b-c)y=0 \\ y=-a \end{array}\right.$ The line $MK$ goes through the fixed point $(c-b,-a)$.