[" 19."cos^(-1)(cos(7 pi)/(6))pi pi pi pi sin theta],[[" (A) "(7 pi)/(6)," (B) "*(5 pi)/(6)," (C) "(pi)/(3)," (D) "(pi)/(6)]]

cos^(-1)((cos(7 pi))/(6)) is equal to ( a ) (7 pi)/(6) (B) (5 pi)/(6) (C) (pi)/(3)(D)(pi)/(6)

cos^(-1)(cos((7pi)/6)) is equal to (A) (7pi)/6 (B) (5pi)/6 (C) pi/3 (D) pi/6

cos ^(-1)(cos ((7 pi)/6)) is equal to A) (7 pi)/6 B) (5 pi)/6 C) pi/3 D) pi/6

Prove that (i) " tan"^(2) .(pi)/(3) + 2cos^(2) .(pi)/(4)+ 3 sec^(2).(pi)/(6)+ 4 cos^(2).(pi)/(2)=8 (ii) " sin ".(pi)/(6) " cos 0 + sin ".(pi)/(4) " cos " .(pi)(4) + " sin " .(pi)/(3) "cos " .(pi)/(6) =(7)/(4) (iii) " 4sin " (pi)/(6) " sin"^(2) (pi)/(3) + 3 " cos " .(pi)/(3) " tan ".(pi)/(4) = " cosec"^(2).(pi)/(2)=4

Find the value of cos^(-1)(cos""(pi)/(7)cos""(pi)/(17)-sin""(pi)/(7)sin""(pi)/(17))

cos""(pi)/(7)+cos""(2pi)/(7)+cos""(3pi)/(7)+......cos""(6pi)/(7)=?

cos^(2)(""(pi)/(6) + theta ) -sin^(2)""((pi)/(6) - theta ) =

(cos pi) / (5) + (cos (2 pi)) / (5) + (cos (6 pi)) / (5) + (cos (7 pi)) / (5) = 0