, we
can use the trigonometric identity 
in order
to convert to a rectangular coordinate system. Because 
and 
above, 
.
We should recognize this to be the equation of a circle with radius
1.Given the parametric equations , we
can use the trigonometric identity in order
to convert to a rectangular coordinate system. Because
and above, .
We should recognize this to be the equation of a circle with radius
1.