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In △ ABC, it is known that ab = L, ∠ C = 50 ° and the length of BC reaches the maximum when ∠ B =
From the sine theorem: BC / sin a = 1 / sin 45 ° and ∵ angle a = 180 ° - 45 ° - angle B ∵ BC / sin (135 ° - angle b) = radical 2 ∵ BC = radical 2 · sin (135 ° - angle b) is expanded to BC = radical 2 · (radical 2 / 2 CoSb + radical 2 / 2 SINB), that is, BC = radical 2 · sin (45 ° + b) ∵ in this triangle, 0 ∵
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