Решите 1 вариант ( В-1 )
Соs60=ab/ad
Ad=ab/cos60=20*1/2=40
Соs45=ab/ac
Ac=ab/cos45=20*2/√2=40/√2
cos60=20/AD=1/2, AD=40
cos45=20/AC=\/2/2, AC=20\/2