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

Statement I : sin^2pi/8+sin^2(3pi)/8+sin^2(5pi)/8+sin^2(7pi)/8=2 Statement II cos^2pi/8+cos^2(3pi )/8+cos^2(5pi)/8+cos^2(7pi/8)=2 Statement III: sin^2pi/8+sin^(3pi)/8+sin^2(5pi)/8sin^2 (7pi)/8=3/2

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

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

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

Prove that: sinpi/7+sin(2pi)/(7) + sin(8pi)/7 + sin(9pi)/7=0

Prove (i) "sin"^(2)(pi)/(8)+"sin"^(2)(3pi)/(8)+"sin"^(2)(5pi)/(8)+"sin"^(2)(7pi)/(8)=2 (ii) [1+cotalpha-sec((pi)/(2)+alpha)] [1+cotalpha+sec((pi)/(2)+alpha)]=2cotalpha

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

4.Prove that sin^(2)((pi)/(8))+sin^(2)((3 pi)/(8))=1