I'm dazzled by this -- it can be solved by graphing.
You can make the substitution 1 - 2sin²(x) = cos(2x)
to get: 4cos(x)cos²(x-1) + cos(2x) = 0,
but ...
2cos(x)(2cos(x-1)^2)+1=2sin(x)^2
The left side function is certainly a strange one........there are two solutions on [0, 360] ....one at 60.4° and the other at 300.4°..........here is the graph.......https://www.desmos.com/calculator/whgq6txzmz