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MathNet 2006 — Part 04 Question 31

Math Olympiad Vault · MathNet 2006 — Part 04

Question 31

Let $ABC$ be a triangle and let $A'$ be the symmetric of $A$ with respect to $BC$; then let $DAA'$ be similar to $ABC$ and let $D'$ be the symmetrical of $D$ with respect to $AA'$. Knowing that the product of the areas of the quadrilaterals $ABA'C$ and $ADA'D'$ is $16$, we can say that $AA'$ ...


(A) is $1$

(B) is $2 \sqrt[4]{2}$

(C) is $2$

(D) is $2 \sqrt{2}$

(E) is not uniquely determined by the data. (Note: the similarity between $DAA'$ and $ABC$ must be understood in an orderly way: $DA/AB = AA'/BC = A'D/CA$ )