\
Step 1 :
\Rotation formula :
\If the x and y-axes are rotated through an angle
, the coordinates
of a point P relative to the xy -plane and the coordinates
of the same point relative to the new x and y-axis and are related by the formulas
and
.
The general form is
The angle is
.
Step 2 :
\The equation is
.
Compare
with 
and
.
The angle is
.
Substitute
and
in

Step 3 :
\Rotation of x - axis :
\
.
Substitute
in above equation.

Rotation of y - axis :
\
.
Substitute
in above equation.

The rotation formulas are
and
..
Step 4 :
\Substitute
and
in
.
Divide each side 12.
\
The above equation is an ellipse.
\\
\
Step 6 :
\\
The graph of the function
.
Solution :
\The equation of an ellipse is 
The graph of the function
.