`cot 6^0 cot 42^0 cot 66^0 cot 78^0=1`

If A =tan6^0tan42^0 and B=cot66^0cot78^0 , then

cot16^0cot44^0+cot44^0cot76^0-cot76^0cot16^0 = (a) 1 (b) 2 (c) 3 (d) 4

Prove that: t a n 225^0cot 405^0+t a n 765^0cot 675^0=\ 0

Prove that: tan6^0tan42^0tan66^0tan78^0=1.

If A = tan 6^@ tan 42^@ and B = cot 66^@ cot 78^@, then

The value of (tan55^0)/(cot35^0)+cot1^0cot2^0cot3^0cot90^0,i s -2 (b) 2 (c) 1 (d) 0

Value of (3+cot80^0cot20^0)/(cot80^0+cot20^0) is equal to (a) cot20^0 (b) tan50^0 (c) cot50^0 (d) cotsqrt(20^0)

Without using trigonometric tables, evaluate the following: (sec37^0)/(cos e c53^0)+2cot15^0cot25^0cot45^0cot75^0cot65^0(sin^2 18^0+sin^2 72^0)

Prove that : tan 225^@ cot 405^@+ tan 765^@ cot 675^@=0

The value of (cot84^(@)cot48^(@))/(cot66^(@)cot78^(@)) is equal to