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

Prove that: tan10^(@)tan50^(@)+tan50^(@)tan70^(@)+tan70^(@)tan170^(@)=3

Prove that: (a) tan 20^(@)tan40^(@)tan60^(@)tan 80^(@)=3 (b) tan9^(@)-tan27^(@)-tan63^(@)+tan81^(@)=4

Show that: tan 10^(@)tan 15^(@) tan 75^(@)tan 80^(@)=1

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

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

Prove that: i) tan36^(@)+tan9^(@)+tan36^(@)tan9^(@)=1

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

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

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

Evaluate tan20^(@)tan25^(@)tan65^(@)tan70^(@) .