`tan 70^(@) -tan 20^(@) - 2 tan 40^(@) = 4 tan 10 ^(@).`

tan 20^(@) tan 40^(@) tan 80^(@) = tan 60^(@)

Prove that tan 9^(@) - tan 27^(@) -tan 63^(@) + tan 81^(@) =4

Prove that tan40^(@) + 2tan10^(@) = tan50^(@)

Evaluate without using trigonometric tables : tan 20^(@) tan 40^(@) tan 50^(@) tan 70^(@)

Prove that : tan 70^(@) = tan 20^(@) + 2 tan 50^(@)

The terms tan80^(@), tan70^(@)+tan10^(@) and tan10^(@) are in

(tan8 0^(@)-tan1 0^(@))/tan70^(@)

If 2a=2tan10^(@)+tan50^(@), 2b=tan20^(@)+tan50^(@) 2c=2tan10^(@)+tan70^(@), 2d=tan20^(@)+tan70^(@) Then which of the following is/are correct ?

Without using trigonometric tables , prove that : (i) tan20^(@)tan40^(@) tan45^(@)tan50^(@)tan70^(@)=1 (ii) tan1^(@) tan2^(@)tan60^(@)tan88^(@)tan89^(@)=sqrt(3) (iii) cot5^(@)cot10^(@)cot30^(@)cot80^(@)cot85^(@)=sqrt(3) (iv) 4sin10^(@)sin20^(@)sin30^(@)sec70^(@)sec80^(@)=2

tan^(6)20^(@) - 33tan^(4) 20^(@) + 27 tan^(2) 20^(@) + 4=