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2014-04-19T20:35:42+03:00
ΔABC,mas<A=90
AD²=BD*DC
8²=4*DC
64=4*DC
DC=16
BC=4+16=20
AB²=BD*BC
AB²=4*20
AB²=80    AB=4√5
AC²=16*20
AC²=320    AC=4√10
sin<B=AC/BC=4√10/20= √10/5
sin<C=AB/BC=4√5/20=√5/5
sin<B+sin<c=√10+√5/5
tr ADC mas<D=90 ACpatrat=ADpatrat+DCpatrat =8patrat+16patrat=64+256=320
AC=8v5 tr ABD mas<D=90 sin<B=AD/AB=8/4v5=2/v5 rationalizam 2v5/5
sin<B+sin<C=2v5/5 +v5/5= 3v5/5
Asta este!
calculasem aria la cealalta problema