To Find: General solution.

Given: cos x + sin x = 1 cos(x - ) = = cos

[divide on both sides and cos(x-y) = cos x cos y - sin x sin y]

Formula used: cos = cos = 2k , k I

x - = 2k x = 2k + x = 2k + or x = 2k +

x = 2k + or x = 2k

So general solution is x = 2n + or x = 2n where n I