sin (pi/16)=?

sin(pi/12)=? sin(11*pi/3)=? 三角函数恒等变形证明sin( pi/3 ) + sin( 2*pi/3) + ...+ sin( n * pi/3)= sin pi/6是正的? pi=派 tana=2求sin(pi-a)cos(2pi-a)sin(-a+3pi/2)/tan(-a-pi)sin(-pi-a) 求助：用matlab把xn=sin(0.2*pi*n)+sin(0.4*pi*n)+sin(0.6*pi*n)+rand 哪位大哥能把xn=sin(0.2*pi*n)+sin(0.4*pi*n)+sin(0.6*pi*n)+randn(siz log((sin(5))^2)-3+pi=? sin（pi/2+x）=? log((sin(30))^2)-3+pi= 证明sin(pi/n)*sin(2pi/n)*sin(3pi/n)*…sin((n-1)pi/n)=n/(2^(n-1) 若θ属于(pi/4,pi/2),sin2θ=1/16,则cosθ-sinθ=?