sinx=a ^a≤1 x1=x0+2kΠ x2=(Π-x0)+2kΠ x0∈<-Π/2, Π/2>	cosx=a ^a≤1 x1=x0+2kΠ x2=-x0+2kΠ x0∈<0, Π>
tgx=a x1=x0+kΠ x0∈(-Π/2, Π/2)	ctgx=a x1=x0+kΠ x0∈(0, Π)