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

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

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

The value of tan 6^(@) tan 42^(@) tan 66^(@) tan 78^(@) is

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

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

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