Prove that :
`tan 20° tan 35° tan 45° tan 55° tan 70° = 1 `

Show that tan 3x tan 2x tan x = tan 3x - tan 2x - tan x

Prove that tan^(-1) 2 + tan^(-1) 3 = (3pi)/4

By using above basic addition/ subtraction formulae, prove that (i) tan (A+B)=(tan A+tan B)/(1-tan A tan B) , (ii) tan (A-B)=(tan A-tanB)/(1+tan A tan B) (iii) sin2theta=2sintheta costheta , (iv) cos2theta=cos^(2)theta=1-2sin^(2)theta=2cos^(2)theta-1 (v) tan 2theta=(2 tan theta)/(1-tan^(2) theta)

Prove that, tan3A.tan2A.tanA=tan3A-tan2A-tanA

Prove that 4 tan^(-1) . 1/5 - tan^(-1) . 1/70 + tan^(-1) . 1/99 = pi/4

Prove that tan^(-1). 1/2 + tan^(-1) . 1/5 + tan^(-1). 1/8 = pi/4

Show that tan 48^(@) tan 16^(@) tan42^(@) tan 74^(@) =1

Prove that: tan^(-1) \ 2/3=1/2tan^(-1) \ 12/5

Prove that f(x) = [tan x] + sqrt(tan x - [tan x]) . (where [.] denotes greatest integer function) is continuous in [0, (pi)/(2)) .

Prove that, tan65^(@)=tan25^(@)+2tan40^(@) .