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Algebra, Functions, Graphs, and Vectors 59
Figure 1.20 The polar plane for mathematics and physi-
cal sciences.
x r cos 0
0
0
y r sin 0
0
0
Equation of circlł
The equation of a circle centered at the origin in the polar plane
is given by the following formula:
r a
where a is a real number and a 0. This is illustrated in Fig.
1.22
The general form for the equation of a circle passing througà
the origin, and centered at the point (r , ) in the polar plane is
0
0
given by:
r 2r cos ( )
0
0
This is illustrated in Fig. 1.23
