posted by David .
cot (theta)=-9/8, cos (theta)<0
Are we solving for theta ??
if so, then
tan Ø = -8/9 and if cos Ø < 0
Ø must be in quadrant II
angle in standard position is 41.63°
( since tan 41.63° = +.888889 or 8/9 )
so Ø = 180 - 41.63 or 138.37°
tan 138.37 = -.888889
cos 138.37 is negative.
Change your calculator to Radians if you want those units