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Multiple Choice
Identify whether the given equation is that of a cardioid, limaçon, rose, or lemniscate. r=3+2cosθ
A
Cardioid
B
Limacon
C
Rose
D
Lemniscate
Verified step by step guidance
1
First, recognize the general form of polar equations. A cardioid has the form r = a + a cos(θ) or r = a + a sin(θ). A limaçon has the form r = a + b cos(θ) or r = a + b sin(θ), where a ≠ b. A rose curve has the form r = a cos(nθ) or r = a sin(nθ). A lemniscate has the form r^2 = a^2 cos(2θ) or r^2 = a^2 sin(2θ).
Examine the given equation: r = 3 + 2 cos(θ). Compare it to the general forms of the polar equations mentioned above.
Notice that the equation r = 3 + 2 cos(θ) fits the form of a limaçon, which is r = a + b cos(θ) or r = a + b sin(θ), where a ≠ b.
In this equation, a = 3 and b = 2. Since a ≠ b, this confirms that the equation represents a limaçon.
Therefore, based on the comparison with the general forms, the given equation r = 3 + 2 cos(θ) is identified as a limaçon.