`cos (cos^-1 cos((8pi)/7) +tan^-1 tan(8pi/7))` has the value equal to -

If A+B+C=pi & cos A = cos B . Cos C then tan B . Tan C has the value equal to

Evaluate : cos^(-1)(cos""(13pi)/6)+tan^(-1)(tan""(7pi)/6) .

If A=sin((2pi)/7)+sin((4pi)/7)+sin((8pi)/7) and B=cos((2pi)/7)+cos((4pi)/7)+cos((8pi)/7) then sqrt(A^2+B^2) is equal to

Show that sin ^ (- 1) ((sin (3 pi)) / (7)) + cos ^ (- 1) ((cos (46 pi)) / (7)) + tan ^ (- 1) (- (tan (13 pi)) / (8)) + cot ^ (- 1) (cot (- (19 pi) / (8))) = (13 pi) / (7)

The value of sin^(-1)(sin((47 pi)/(7)))+cos^(-1)cos((60 pi)/(7))+tan^(-1)(-(tan)(29 pi)/(8))+cot^(-1)(cot(-(35 pi)/(8)))

If sin^(-1)(sin.(33pi)/(7))+cos^(-1)(cos.(46pi)/(7)) + tan^(-1)(-tan.(13pi)/(8))+cot^(-1)(-cot.(19pi)/(8))=(api)/(b) , where a and b are constant, then (a+b) is equal to

Let alpha = tan^-1 (1/2)+tan^-1(1/3) , beta=cos^-1(2/3)+cos^-1(sqrt5/3) , gamma=sin^-1(sin((2pi)/3))+1/2cos^-1(cos((2pi)/3)) The value of cos(alpha+beta+gamma) is equal to (A) cos((5pi)/12) (B) cos ((7pi)/12) (C) -cos(pi/12) (D) -cos ((7pi)/12)

Let alpha = tan^-1 (1/2)+tan^-1(1/3) , beta=cos^-1(2/3)+cos^-1(sqrt5/3) , gamma=sin^-1(sin((2pi)/3))+1/2cos^-1(cos((2pi)/3)) The value of cos(alpha+beta+gamma) is equal to (A) cos((5pi)/12) (B) cos ((7pi)/12) (C) -cos(pi/12) (D) -cos ((7pi)/12)