How do you graph #2=r cos(θ + 180°)#?

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Answer 1 · 2016-02-15T10:02:57

it is a vertical Line #x=-2#

From the given

#2=r*cos (theta+180)#

#2=r*[cos theta cos 180-sin theta sin 180]#

#2=r*[cos theta(-1)-sin theta (0)]#

#2=r*(-cos theta-0)#

#2=-r*cos theta#

recall #r=sqrt(x^2+y^2)# and #cos theta=x/sqrt(x^2+y^2)#

and the equation becomes

#2=-sqrt(x^2+y^2)*x/sqrt(x^2+y^2)#

#2=-cancelsqrt(x^2+y^2)*x/cancelsqrt(x^2+y^2)#

#2=-x#
and

#x=-2" " "# a vertical line which is the equivalent of

#2=r*cos (theta+180)#

graph{y=1000000x+21000000[-10,10,-5,5]}

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