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2014-04-22T16:37:43+03:00
ΔBAD, mas<D=90
BD²=AB²-AD²=400-144=156   ⇒BD=16
AB²=BD*BC
400=16*BC
BC=25
DC=25-16=9
AC²=BC²-AB²=625-400=225    ⇒AC=15
sin<B=AC/BC=15/25=3/5
cos<CAD=DC/AC= 9/15=3/5
tg<C=AB/AC=20/15=4/3