Prove that: `sin(pi/5)sin( (2pi)/5)sin(3pi/5)sin(4pi/5)=5/(16)`

Prove that: sin(pi/5) sin2pi/5 sin3pi/5 sin4pi/5=5/16

Prove that: sin((3pi)/8-5)cos( pi/8+5)+cos((3pi)/8-5)sin(pi/8+5)=1

sin^(-1)sin((3pi)/5)

Prove that: cos(pi/5)cos((2pi)/5)cos((4pi)/5)cos((8pi)/5)=(-1)/16

Prove that: sin^4(pi/8)+sin^4((3pi)/8)+sin^4((5pi)/8)+sin^4((7pi)/8)=3/2

Prove that: sin(pi/14)sin((3pi)/14)sin((5pi)/14)sin((7pi)/14)sin((9pi)/14)sin((11pi)/14)sin((13pi)/14)=1/(64)

Prove that; 2sin((5pi)/12)sin(pi/12)=1/2

Prove that: sin^2(pi/8)+sin^2((3pi)/8)+sin^2((5pi)/8)+sin^2((7pi)/8)=2

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

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