Consider a line l with positive x- and y- intercepts. suppose l makes an angle of with the positive x- axis. what is the slope of l in terms of theta?

Check the picture. 

line l is the orange line, intersecting the positive x-axis and the positive y axis. 

The angle with measure ∅ is the angle made by the line and the positive x-axis. It is the obtuse (>90° angle) shown in the picture.

the slope of the line l is tan∅