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MathNet 2015-part-07 — 185 problems (EN–VI) Question 52

Math Olympiad Vault · MathNet 2015-part-07 — 185 problems (EN–VI)

Question 52

Let $ABCDE$ be a square pyramid of height $\frac{1}{2}$ with square base $ABCD$ of side length $AB=12$ (so $E$ is the vertex of the pyramid, and the foot of the altitude from $E$ to $ABCD$ is the center of square $ABCD$). The faces $ADE$ and $CDE$ meet at an acute angle of measure $\alpha$ (so that $0^{\circ}\lt\alpha\lt 90^{\circ}$). Find $\tan \alpha$.