`cot(pi/12) + cot((3pi)/12) + cos ((9pi)/12)+ cos ((11pi)/12)`

tan((11pi)/12)

cot ((pi) / (12)) + cot ((3 pi) / (12)) + cos ((9 pi) / (12)) + cos ((11 pi) / (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)

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)

cos(pi/12)+sin^2((3pi)/12)+sin^2((9pi)/12)+cos((11pi)/12)=...

Prove that cos(pi/12)+cos(3pi/12)+cos(9pi/12)+cos(11pi/12)=0

cos. (pi)/(13) + cos. (5pi)/(13) + cos. (8pi)/(13) + cos. (12pi)/(13)=

Prove: (ii) tan ((pi)/12) tan ((5 pi)/12) tan ((7 pi)/12) tan ((11 pi)/12) = 1

cot. (pi)/(20) cot. (3pi)/(20) cot. (5pi)/(20) cot. (7pi)/(20) cot. (9pi)/(20) cot. (15pi)/(20)=

Find the value of 2cos((5 pi)/(12))cos((pi)/(12)) and 2sin((5 pi)/(12))cos((pi)/(12))