Question 164
If real numbers $a, b, c, d$ satisfy
$$
\frac{a+b}{c+d} = \frac{b+c}{a+d} \neq -1,
$$
prove that $a = c$.
$$
\frac{a+b}{c+d} = \frac{b+c}{a+d} \neq -1,
$$
prove that $a = c$.
MathNet 2009-part-04 — 175 problems (EN–VI) Question 164
Math Olympiad Vault · MathNet 2009-part-04 — 175 problems (EN–VI)