геом пр.: bn=b1qn-1 Sn=b1(1-qn)/(1-q)
спадна: S=b1/(1-q)
Вектори: a·b=x1x2+y1y2+z1z2
|a|=Öx2+y2+z2 a+b=c(xa+xb;ya+yb)
cos(a^b)=(a·b)/|a|·|b| a·b=xa·xb+ya·yb
a | b®a·b=0 a||b®xa/xb=ya/yb
|l·a|=|l|·|a|
logaxy=logax+logay logax/y=logax-logay
logax=logbx/logba