This task was just to solve this equation: $\cos2x=\cos4x$. I solved it correctly apart from one step. My book somehow changes $-n\cdot \pi $ to $n\cdot \pi $. How is it possible?
2026-04-05 12:08:24.1775390904
Why can $-n\cdot \pi $ be changed to $n\cdot \pi $?
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