We need to sketch `r = 2.5`

In this example, we cannot see "*θ*" in the
function we are given. This means the radius, *r* is **constant**, no
matter what value angle *θ* takes.

Here's the graph:

Graph of *r* = 2.5, a limacon.

We convert the function given in this question to rectangular coordinates to see how much simpler it is when written in polar coordinates.

To convert `r = 2.5` into **rectangular coordinates**,
we use

r^{2}=x^{2}+y^{2}

In this example, `r = 2.5`, so `r^2= 6.25`.

So this gives us: *x*^{2} + *y*^{2}
= 6.25

Not surprisingly, this is the similar to the equation for a circle we obtained in The Circle section earlier.

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