` (tan 66^(@) + tan 69^(@) )/( 1-tan 66^(@) tan 69^(@) )= `

Simplify be reducing to a single term : (tan 69^(@) + tan 66^(@))/(1 - tan 69^(@) tan 66 ^(@))

Prove that (i) "cos " 15^(@) - " sin " 15^(@) = (1)/(sqrt(2)) (ii) " cot " 105^(@) - " tan " 105^(@) =2sqrt(3) (iii) (tan 69^(@) + tan 66^(@))/(1-tan 69^(@) tan 66^(@)) =-1

If tan 69^(@) + tan 66^(@) - tan 69^(@)tan 66^(@) = 2k then k = (a) -(1)/(2) (b) (1)/(2) (c) -1 (d)None of these

tan 6 ^(@) tan 42 ^(@) tan 66 ^(@) tan 78^(@) =1

Show that, tan 181^(@) tan182^(@) tan 183^(@).....tan 267^(@) tan 268^(@) tan 269^(@) = 1 .

Prove that (tan69^(@)+tan66^(@))/(1-tan69^(@)tan66^(@))=-1

Prove that :(tan69^(@)+tan66^(@))/(1-tan69^(@)tan66^(@))=-1