(tan69^(@)+tan68^(@))/(1-tan69^(@)tan66^(@))=-1

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

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

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

Prove that :(tan69^@+tan 66^@)/(1-tan 69^@tan66^@)=-1

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

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

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

Prove that:(i) "tan"69^(@)+"tan"66^(@)+1="tan"69^(@) "tan"66^(@) (ii) (cos13^(@)+"sin"13^(@))/(cos13^(@)-"sin"13^(@))="tan"58^(@)

If tan 69^(@) + tan 66^@ - tan 69^(@) tan66^@=2k , then the value of k is