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MathNet 2020 — Math Olympiad Vault — Part 03 Question 103

Math Olympiad Vault · MathNet 2020 — Math Olympiad Vault — Part 03

Question 103

Two congruent squares $ABCD$ and $EFGH$ are placed such that they have disjoint interiors, but $C$ is the midpoint of the line segment $EF$ and the points $B$, $F$, $G$ are collinear. The line $BC$ intersects $EH$ at $K$ and the line $AC$ intersects $GH$ at $M$. Let $L$ be the midpoint of $GH$, and let the parallel through $K$ to $GH$ intersect $FG$ at $N$.

a) Prove that $CK = CL = CN$.
b) Prove that $LM = 2HK$.

Question illustration