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

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

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

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

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

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

Prove that: tan6^0tan42^0tan66^0tan78^0=1.

Prove that tan 20^@tan 40^@ tan 60^@ tan 80^@ = 3

tan20^@tan40^@tan60^@tan80^@=

Prove that: tan20^(@)tan40^(@)tan60^(@)tan80^(@)=3

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