Precalculus with Limits: A Graphing Approach, Sixth Edition
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Precalculus with Limits: A Graphing Approach, Sixth Edition View details
6. Graphs of Polar Equations
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Exercise 1 Page 689

The given equation represents one of the limacons.

convex limacon

We are asked to complete the given statement.

The equation r=2+cos θ represents a .

Let's consider the equations of a limacon. Equations of a Limacon [0.5 em] r= a± bcosθ or r= a± bsinθ

It is noticeable that r=2+cos θ is a limacon equation. Limacons can be classified depending on the a and b values of the equation.

Limacon with Inner Loop Cardioid Dimpled Limacon Convex Limacon
a/b<1 a/b=1 1< a/b< 2 a/b≥ 2

Let's identify the values of a and b in the given equation. Equation of a Limacon [0.5 em] r=2+cos θ ⇕ r= 2+ 1cos θ We can see that a=2 and b=1. Therefore, the following inequality is true. Convex Limacon Condition [0.5 em] a/b≥ 2 ⇔ 2/1≥ 2 ✓ We found that the given equation represents a convex limacon. Let's take a look at its graph.

limacon

The graph confirms our answer. Finally, we can complete the given statement.

The equation r=2+cos θ represents a convex limacon.