TRIGONOMETRY - Temperature in Cincinnati

Take the xy-plane and
draw a circle of radius ONE.
The equation for this circle is
x^2 + y^2 = 1.
If you wish to use the graphing
calculator to draw the circle you
will need to split it into two
functions. (It is not a function itself!)
y1 = ( 1 - x^2)^(1/2)
y2 = (-1)( 1 - x^2)^(1/2)
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Draw an angle "SMILE" in a
STANDARD POSITION
(start with a side along the x-axis and then rotate
counter-clockwise a certain number of degrees).
The side along the x-axis is called the initial side
and the other side is the terminal side.
The TERMINAL SIDE will intersect the unit circle
at an ordered pair.
This ordered pair is by definition:
the COSINE and SINE of the ANGLE drawn.
Thus, a 30 degree angle will intercept
the circle at the ordered pair (.5, .8660254).