cosx/2*cosx/4…*cosx/2的n次方
=cosx/2*cosx/4…*cosx/2的n次方 ×2的n次方×sinx/2的n次方/[2的n次方×sinx/2的n次方]
=cosx/2*cosx/4…*cosx/2的n-1次方 ×2的n-1次方×sinx/2的n-1次方/[2的n次方×sinx/2的n次方]
=.
=2cosx/2sinx/2/[2的n次方×sinx/2的n次方]
=sinx/[2的n次方×sinx/2的n次方]
cosx/2*cosx/4…*cosx/2的n次方
=cosx/2*cosx/4…*cosx/2的n次方 ×2的n次方×sinx/2的n次方/[2的n次方×sinx/2的n次方]
=cosx/2*cosx/4…*cosx/2的n-1次方 ×2的n-1次方×sinx/2的n-1次方/[2的n次方×sinx/2的n次方]
=.
=2cosx/2sinx/2/[2的n次方×sinx/2的n次方]
=sinx/[2的n次方×sinx/2的n次方]