CosM=sinM

cosM=cosN

cosM=tanN

SinM=cosM

tanM=tanN

Due to the fact that M, according to the original equation, must equal π/4, N would have to equal the same according the next one. Though, everything falls apart on cosM=tanN. Because cos (π/4) ≠tan (π/4). Though, everything works out for the rest.