Respuesta :

chudung1976
We have the formula tan(a+b)= (tana+tanb): (1-tana x tanb)
And now we have a=80, b=70 and
(tan80+tan70): (1-tan80 x tan70)= tan(80+70)= tan150
If you write 70 for 70°, we have tan150°=1/√3
Merry Christmas