How do you graph #r= 5 cos theta #?

1 Answer
A. S. Adikesavan
Feb 23, 2016

Draw a circle with center at polar (5/2, 0 ) and radius 5/2.

Explanation:

r = D cos #theta# is the equation of the circle with center on the

initial line #theta# = 0, at a distance D/2. D is diameter of the circle.

The general equation of circles passing through the pole is

#r = D cos( theta -alpha) = 0#, representing the circle through r =

  1. Here, the diameter is D and the center is at #( D/2, alpha )#.

The graph contrasts four such circles with D = 5 ( radius 2.5 ) and

#alpha = 0, pi/2, pi, 3/2pi#.

graph{(x^2+y^2-5x)(x^2+y^2-5y)(x^2+y^2+5x)(x^2+y^2+5y)=0[-10.2 10.2 -5.6 5.6]}

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