※ 引述《mrjj123 (RRRRRRRR)》之銘言：
: https://i.imgur.com/1QFLkqp.jpg
: 請問這題要怎麼算呢
連BD&DA
則由"中定"
CD^2+1^2=2(DA^2+1^2)
CD^2=2[(4sin^2DBA)]+1
=2[2(1-cosDOA)]+1
=5-4cosDOA
面積OCED
=[(sqrt3)/4](5-4cosDOA)+(1/2)*1*2*sin(2DBA)
=[(5sqrt3)/4]-(sqrt3)cosDOA+sinDOA
<= 2+[(5sqrt3)/4]...ans
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※ 編輯: wayne2011 (61.58.103.35), 10/07/2017 10:42:55