task/29997333 cos0 = 1 ; неопределенность типа 0 / 0
2xsinx /(1 -cosx) =2x*2sin(x/2)*cos(x/2) / 2sin²(x/2) =2xcos(x/2) /sin(x/2) =
4cos(x/2) * (x/2) / sin(x/2) = 4cos(x/2) : ( sin(x/2) / (x/2) ) .
iim 2xsinx /(1 -cosx) = lim [ 4cos(x/2) : ( sin(x/2) / (x/2) ) ] =
lim [ 4cos(x/2) / lim ( sin(x/2) / (x/2) ) ] = 4 / 1 = 4 .
везде x → 0 * * * под lim * * *
ответ : 4
ИЛИ
lim 2xsinx /(1 -cosx) =iim (2xsinx) /(1 -cosx) =iim (2xsinx) ' / (1 -cosx) ' =
iim 2(sinx +xcosx) /sinx = 2iim [ 1 +cosx / (sinx) / x ] =
2* [1 +limcosx / lim sinx / x ] =2(1+1/1) =2*2 = 4. правило Лопиталя для вычисления пределов