Question 124
Points $A_1, B_1$ are marked on the sides $AC$ and $BC$ of the triangle $ABC$, respectively, so that $A_1B_1 \parallel AB$. Points $A_2, B_2$ are the feet of perpendiculars from $A_1, B_1$ onto $AB$, respectively.
Prove that $AC = AB_2 + CB_1$ if and only if $BC = BA_2 + CA_1$.
(I. Voronovich)
Prove that $AC = AB_2 + CB_1$ if and only if $BC = BA_2 + CA_1$.
(I. Voronovich)