Prove that: `tan20otan35otan45otan55otan70o=1`

Prove that tan70=2tan50+tan20

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: tan20^(@)tan30^(@)tan40^(@)tan80^(@)=1

Write the value of tan10otan15otan75otan80o .

Prove that (tan25^(@)-tan35^(@)+tan85^(@))/(tan25^(@)tan35^(@)tan85^(@))=3

Prove that: tan70^(@)=tan20^(@)+2tan50^(@)

Prove that tan70^(@)=2tan50^(@)+tan20^(@)

prove that- (1+tanx)/(1-tanx)=tan(45+x)

The value of tan10otan15otan75otan80o is -1 (b) 0 (c) 1 (d) None of these

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