Решение:
∠CAB = 176° ÷ 2 = 88°
∠ACD = 108° ÷ 2 = 54°
∠AEC = 180° - 88° - 54° = 38°
∠BEC = 180° - 38° = 142°
Ответ: ∠BEC = 142°
1) 26+38+4+2=38+2+26+4=40+30=70
2)49+6+11+4=49+11+6+4=60+10=70
3)19+20+1+10=19+1+20+10=50
4)45+28+5+63+7+20=45+5+63+7+28+20=50+70+48=120+48=168
5)27+3+4+6=30+10=40
A²b²/(a-b)²:ab/2a-2b =2a²b²(a-b)/(a-b)²ab = 2ab/a-b. При a = √7-2, b = √7+2: 2*(√7-2)(√7+2)/√7-2-√7-2 = 2*(7-4)/-4 =3/-4 =>-3/4
<span>7 1/5 : 2 2/5 = 0,9:х
3=0,9:x
x=0,9:3
x=0,3</span>