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MathNet 2017-part-05 — 176 problems (EN–VI) Question 33

Math Olympiad Vault · MathNet 2017-part-05 — 176 problems (EN–VI)

Question 33

Triangle $ABC$ has $\angle A = 90^\circ$, $\angle B = 30^\circ$, and $D$ is the foot of the altitude from $A$. Let $E \in (AD)$ be such that $DE = 3AE$ and let $F$ be the foot of perpendicular from $D$ on $BE$.

a) Prove that $AF \perp FC$.

b) Find the measure of the angle $AFB$.