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1977 AHSME Problems/Problem 4

Revision as of 11:49, 18 November 2016 by E power pi times i (talk | contribs) (Created page with "==Solution== Solution by e_power_pi_times_i Because <math>\measuredangle A=80^\circ</math>, <math>\measuredangle B=\measuredangle C=50^\circ</math>. Then, because triangles <...")
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Solution

Solution by e_power_pi_times_i

Because $\measuredangle A=80^\circ$, $\measuredangle B=\measuredangle C=50^\circ$. Then, because triangles $CDE$ and $BDF$ are isosceles, $\measuredangle CDE=\measuredangle BDF=65^\circ$. $\measuredangle EDF=180^\circ - 2(65^\circ)=\textbf{(C) }50^\circ$

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