<span>CosL,tgL,если ctg = -2
tg = 1/ctg tgL=1/(-2)=-1/2 = -0.5
cos = +-</span>√(1/(1+1/ctg²)) cosL= +- √(1/(1+1/4))=+-√(1/ 5/4))= +-2√5/5
А1-а4=6
- 3d=6
d= - 2
a3+a6=2
a1+2d+a1+5d=2
2*a1+7d=2
2*a1+7*(-2)=2
2*a1 - 14=2
2*a1=16
a1=8
a5=a1+4d=8+4*(-2)=8-8=0
2х²-х²-5х-3х-2+2=х²-8х=х(х-8)