Incep,cu,b),ca,este,mai,simplu
Din,D,si,C,ducem,perpendiculare,pe,AB,si,notam,picioarele,acestora,cu,M,si,N.Segmentul,MN=CD=12=>AM=NB=(30-12)/2=9
S-au,format,doua,tr.dr.AMD,si,BNC,din,care,aflam,cu,t.Pit.,oricare,dintre,inaltimile,DM,sau,CN
CN²+NB²=CB²=>CN²=CB²-NB²=>CN²=225-81=>CN²=144=>CN=12
Aria,trapez=(B+b)h/2=(30+12)12/2=42x6=>Aria=252cm²
a)Trasam,diag.AC
Avem,tr.dr.ACN,in,care,cunoastem,CN=12,AN=9+12=21,aflam,cu,t.Pit.diagonala,AC:
AC²=CN²+AN²
AC²=144+441
AC²=585=>AC=3√65cm
