Unit circle interpretation of sin(0) = cos(0)?

Since x = cos θ and y = sin θ on the unit circle, sin θ = cos θ must be where the line x = y intersects the unit circle. This would be where θ = π/4 and where θ = π + π/4 = 5π/4.

Since the sine of an angle is the y-coordinate, and the cosine is the x-angle, you have to find the points on the unit circle whose x-coordinate is equal to its y-coordinate; the answers are pi/4 and 5 pi/4

sinθ=cosθ when θ=pi/4 and 5pi/4 QI and QIII where both sin and cosine have the same signs