`(4sin^2 9^@-3)(4sin^2 2 7^(@)-3)` is equal to -

If K=sin^(-1)(sin16) then sin^(-1)(sin(K-5 pi+23)) is equal to "],[7-2 pi],[2 pi-7],[3 pi-9],[9-3 pi]

(sin((2 pi)/(7))+sin((4 pi)/(7)) -sin((6 pi)/(7)))/(sin((pi)/(7))sin((3 pi)/(7))sin((5 pi)/(7))) is equal to

(sin^(2)1^(@) + sin^(2)3^(@) + sin^(2)5^(@) +sin^(2)7^(@) + ….. + sin^(2)87^(@) + sin^(2)89^(@)) equals

If pi