题目
如图,平面四边形A BCD中, AB=8 ,CD=3 ,-|||-=5sqrt (3) angle ADC=(90)^circ angle BAD=(30)^circ ,点E,F-|||-满足 overrightarrow (AE)=dfrac (2)(5)overrightarrow (AD) overrightarrow (AF)=dfrac (1)(2)overrightarrow (AB) ,将 Delta AEF 沿EF-|||-翻折至 Delta PEF ,使得 =4sqrt (3) 。-|||-(1)证明: bot PD ;-|||-(2)求平面PCD与平面PBF所成的二面角的-|||-正弦值.-|||-P-|||-A E-|||-D-|||-F-|||-B-|||-C

题目解答
答案



