Look at the right triangle in each quadrant and the signs of the coordinates of A. Based on that, determine the sign of the trigonometric ratios in each quadrant.
The signs of trigonometric ratios in Quadrant II are:
sin([math]\alpha[/math])
cos([math]\alpha[/math])
tan([math]\alpha[/math])
The signs of trigonometric ratios in Quadrant III are:
sin([math]\alpha[/math])
cos([math]\alpha[/math])
tan([math]\alpha[/math])
The signs of trigonometric ratios in Quadrant IV are: