The equation is
.
Take tangent on both sides.
\
.
From circular function definitions
, where
is an angle.
.

The graph of this equation is a line through the origin with slope
.
Evaluate the function for several values of
in its domain and use this points to graph the function.
(1) Draw the coordinate plane.
\(2) Graph the function
.
Graph :
\
The rectangular equation is
.
Graph :
\