" If "tan69^(@)+tan66^(@)-tan69^(@)tan66^(@)=2k," then "k" is equal to "

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

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

(tan80^(@)-tan10^(@))/(tan70^(@))=k, then k=?

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

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

If A=tan6^(@)tan42^(@) and B=cot66^(@)cot78^(@), then

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

The value of tan6^(@)tan42^(@)tan66^(@)tan78^(@) is

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