Prove that `tan20^0tan40^0tan80^0=tan60^0`

Prove that tan20^0tan40^0tan60^0tan80^0 =3

Prove that: t a n 20^0tan40^0tan60^0tan80^0=3

Prove that tan70^0=2tan50^0+tan20^0

Prove that tan70^0=2tan50^0+tan20^0

Prove that : tan 20^0 tan 40^0 tan 60^0 tan 80^0 =3

Prove that tan20^(@)tan40^(@)tan80^(@)=tan60^(@) .

Prove that tan20^(@)tan40^(@)tan80^(@)=tan60^(@)

Prove that: tan10^0tan15^0tan75^0tan80^0=1 tan1^0tan2^0tan3^0.....tan89^0=1 cos1^0cos2^0cos3^0.......cos180^0=0

Prove that: tan10^0tan15^0tan75^0tan80^0=1 tan1^0tan2^0tan3^0tan89^0=1 cos1^0cos2^0cos3^0cos180^0=0

Prove that tan20^@tan30^@tan40^@tan80^@=1