(cost)^2-(sint)^2/tg(-a)ctg(a)= (cost)^2-(sint)^2/(-1)= (cost)^2+(sint)^2=1
tg(-a)ctg(a)= -tg(a)ctg(a)=-1
2x - П/4 = ±3П/4 + 2Пk, k∈Z
2x = П + 2Пk и 2x = -П/2 + 2Пk
2x = П + 2Пk 2x = -П/2 + 2Пk
x = П/2 + Пk,k∈Z и x = -П/4 + Пk, k∈Z
<span> 7m−11n, если m=−411, n=47.
7*(-411)-11*(47)= -2877 - 517= - 3394</span>
////////////
///////////////