а(ctg6-ctg4+tg2)=-5.284223584416309a

1) ctg(6)=10.57889499340564

2) ctg(4)=15.8945448438653

3) 10.57889499340564-15.8945548438653=-05.31564985045966

4) tan(2)=0.031426266043351

5)0.031426266043351-5.315649850459660=-5.284223584416309