In Triangle ABC, A:B:C =1:2:4, then TanA x TanB +TanB x TanC + TanC x TanA =

ans is (-7.0044)

given A+B+C=180   A:B:C=1:2:4 SO B=2A , C=4A ?

#   A+2A+4A=180

#7A=180

#A=25.71 DEGREES  B=2A=51.43     C=4A=102.85 

THEN SUBSTITUTE THIS VALUES IN THE GIVEN EQUATIONS.