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本期问题初351在菱形ABCD中,∠A=60°,E为线段CD上一点,延长AE,与BC的延长线交于点F,联结FD,延长BE,与DF交于点G若BG=a,试用a表示四边形BCGD的面积.初352如图1,⊙O_1与⊙O_2内切于点P,点A、B在⊙O_1上,直线AC、BD分别与⊙O_2切于点C、D,直线AB与CD交于点E.证明:(1)AC/BD=AP/BP;(2)PE平分∠APB.高363设a_1,a_2,…,a_n>0.证明:(?)高364一幢建筑物有2~(10)层,第i层有i
In the initial issue of diamond ABCD, ∠A = 60 °, E is the last point on the segment CD, extend the AE, extend the line BC to point F, connect the FD, extend BE, and point DF to point G if BG = a, trial a represents the area of the quadrilateral BCGD. As shown in Figure 1, ⊙O_1 and ⊙O_2 are inscribed at point P, point A and B are at ⊙O_1, and straight lines AC and BD are cut at point C and ⊙O_2 respectively. D, straight line AB and CD intersection point E. Proof: (1) AC / BD = AP / BP; (2) PE bisecting ∠APB. High 363 Let a_1, a_2, ..., a_n> Height 364 A building has 2 ~ (10) layers, the i-th layer has i