# Signs of Trigonometric Functions

Since sin(t) and cos(t) are respectively y-coordinate and x-coordinate of point P_t, that lies on unit circle centered at origin, then sine is positive for points that lie on upper half of the circle and negative for points that lie on lower half of the circle. Cosine is positive for points that lie on right half of the circle and negative for points that lie on left half of the circle.

Signs of all trigonometric functions in each quadrant are shown on figure.