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Multiple Choice
Identify whether the given equation is that of a cardioid, limaçon, rose, or lemniscate. r=1−sinθ
A
Cardioid
B
Limacon
C
Rose
D
Lemniscate
Verified step by step guidance
1
Step 1: Recognize the general form of the polar equation provided, which is r = 1 - sin(θ). This equation is in polar coordinates, where r represents the radius and θ represents the angle.
Step 2: Compare the given equation to the standard forms of polar curves. A cardioid typically has the form r = a ± b*sin(θ) or r = a ± b*cos(θ), where a = b. In this case, the equation matches the cardioid form because the coefficients of 1 and -sin(θ) satisfy a = b.
Step 3: Understand the characteristics of a cardioid. A cardioid is a heart-shaped curve that occurs when the coefficients a and b are equal in the polar equation. This symmetry is evident in the given equation.
Step 4: Eliminate other options by analyzing their standard forms. For example, a limaçon has the form r = a ± b*sin(θ) or r = a ± b*cos(θ) with a ≠ b, a rose curve has the form r = a*sin(nθ) or r = a*cos(nθ), and a lemniscate has the form r² = a²*sin(2θ) or r² = a²*cos(2θ). None of these match the given equation.
Step 5: Conclude that the given equation r = 1 - sin(θ) represents a cardioid based on its form and characteristics.