1) DE = a + 5b/6
DF = b + a/3
2) Sтр = a²/2 sin60
12√3 = a²√3/4
a² = 48√3/√3 = 48
a = √48
√48 = 2R sin60
√48 = √3 R
R = √48/√3 = 4
Sкр = пR² = 3,14 * 16 = 50,24
