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

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 tan50^(@)-tan40^(@)=k tan10^(@) then the value of k is

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

Prove that : tan 69^@ + tan 66^@+ 1 = tan 69^@ tan 66^@ .

If 4(cosec^2 66^@-tan^2 24^@)+1/2 sin90^@- 4tan^2 66^@ y tan^2 24^@=y/2 , then the value of y is: यदि 4(cosec^2 66^@-tan^2 24^@)+1/2 sin90^@- 4tan^2 66^@ y tan^2 24^@=y/2 , है, तो y का मान है:

Prove tan 9^@. tan 21^@.tan 69^@.tan 81^@=1

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

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

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