Quadrantal Angles

These angles have terminal side coinciding with a coordinate axis, thus a trigonometric functional value of such an angle is determined by the coordinates of the point where the terminal side (axis) intersects the unit circle. Recall that, by definition, the point $(x,y)$ on the unit circle corresponds to $(\cos\theta , \sin\theta).$

$\theta$	Point	$\sin\theta$	$\csc\theta$	$\cos\theta$	$\sec\theta$	$\tan\theta$	$\cot\theta$
$0,\;$or$\;0^\circ$	$(1 , 0)$	0	not defined	1	1	0	not defined
$\frac{\pi}{2},\;$or$\;90^\circ$	$(0 , 1)$	1	1	0	not defined	not defined	0
$\pi,\;$or$\;180^\circ$	$(-1 , 0)$	0	not defined	-1	-1	0	not defined
$\frac{3\pi}{2},\;$or$\;270^\circ$	$(0 , -1)$	-1	-1	0	not defined	not defined	0