How do you solve this?

(sinx + cosx)^2 - 1 = sin^2x

(sinx + cosx)^2 - 1 = sin^2x

sin^2x + 2sinxcosx + cos^2 - 1 - sin^2x = 0
2sinxcosx - sin^2x = 0
sinx(2cosx - sinx) = 0
sinx = 0
so x = 0, 180, or 360 OR 0, pi, 2pi
or
2cosx = sinx
2 = sinx/cosx
tanx = 2 , tangent is + in I and III
x = 63.4 degrees or 180+63.4 degrees
(for radian, set your mode on the calculator to rad)