Sin\theta +cos\theta =1

θ = 2 π n_1 + π/2 for n_1 element Z  or θ = 2 π n_2 for n_2 element Z

Step-by-step explanation:

Solve for θ:

cos(θ) + sin(θ) = 1

cos(θ) + sin(θ) = sqrt(2) (cos(θ)/sqrt(2) + sin(θ)/sqrt(2)) = sqrt(2) (sin(π/4) cos(θ) + cos(π/4) sin(θ)) = sqrt(2) sin(θ + π/4):

sqrt(2) sin(θ + π/4) = 1

Divide both sides by sqrt(2):

sin(θ + π/4) = 1/sqrt(2)

Take the inverse sine of both sides:

θ + π/4 = 2 π n_1 + (3 π)/4 for n_1 element Z

or θ + π/4 = 2 π n_2 + π/4 for n_2 element Z

Subtract π/4 from both sides:

θ = 2 π n_1 + π/2 for n_1 element Z

or θ + π/4 = 2 π n_2 + π/4 for n_2 element Z

Subtract π/4 from both sides:

θ = 2 π n_1 + π/2 for n_1 element Z

or θ = 2 π n_2 for n_2 element Z