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

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

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

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

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

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^(@)tan50^(@)+tan50^(@)tan70^(@)+tan70^(@)tan170^(@)=3

Prove that: t a n 70^0=t a n 20^0+2t a n 50^0dot

Prove that: t a n 70^0=t a n 20^0+2t a n 50^0dot

Prove that: tan75^0+cot75^0=4

Prove that: tan10^(@) tan20^(@)tan70^(@)tan80^(@)=1