(sin pi/9)(4+sec pi/9)=?

The value of 3 sin (pi/6) "sec" (pi/3) - 4 sin (5pi/6) cot (pi/4) is-

Hence deduce that cos(pi)/(9)cos(2 pi)/(9)cos(3 pi)/(9)cos(4 pi)/(9)=(1)/(16)

The value of sec[sin^(-1)(-sin""(50pi)/9)+cos^(-1)cos(-(31pi)/9)] is equal to a) sec""(10pi)/9 b) sec""pi/9 c)1 d) -1

( sin (15pi//9)*tan(4pi//3)*sec(-7pi//3))/(cot(-3pi//4)*cos(7pi//6)*"cosec"(-7pi//4))=

sin ^(2) (pi)/(18)+sin ^(2) (pi)/(9)+sin ^(2) (7 pi)/(18)+sin ^(2) (4 pi)/(9)=

Prove that sin ""(pi)/(9) sin ""(2pi)/(9) sin ""( 3pi)/(9) sin ""(4pi)/(9) = (3)/(16).

Value of expression sin(pi/9)+sin((2pi)/9)+sin((3pi)/9)+...+sin((17pi)/9)=

Value of expression sin(pi/9)+sin((2pi)/9)+sin((3pi)/9)+...+sin((17pi)/9)=

Prove that: (sin^(2)pi)/(18)+(sin^(2)pi)/(9)+(sin^(2)(7 pi))/(18)+(sin^(2)(4 pi))/(9)=2