A unit circle is a circle that has a radius of one unit.
Certain trigonometric functions are simpler in unit circles. For example the coordinates of a point on a circle of radius r
are given by
x = r cos(t)
If the radius is one, as in a unit circle then the coordinates simplfy to
y = r sin(t)
x = cos(t)
y = sin(t)
A circle can be defined as the locus of all points that satisfy an equation derived from Trigonometry. Interactive coordinate geometry applet.
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