Solve −cos(x+6π)=sin(x+6π−2π)
=sin(x−3π),
The original equation can be transformed into
sin(x+6π)=sin(x−3π).∴x+6π=nπ+(−1)⋅(x−3π).
When B=2k(k∈Z), the equation becomes
x+6π=2kπ+x−3π, no solution.
When n=2k+1(k∈Z), the equation becomes
x+6π=(2k+1)π−x+3π,x=kπ+127π.
The solution set of the original equation is {x:x=kπ+127π,k∈Z}.