Describe the graph represented by the equation lower r equals start fraction 4 over 2 plus 3 sine theta end fraction.

(1 point)
Responses

ellipse, horizontal directrix at a distance of start fraction 4 over 3 end fraction units above the pole
ellipse, horizontal directrix at a distance of Image with alt text: start fraction 4 over 3 end fraction units above the pole

hyperbola, horizontal directrix at a distance of start fraction 4 over 3 end fraction units above the pole
hyperbola, horizontal directrix at a distance of Image with alt text: start fraction 4 over 3 end fraction units above the pole

hyperbola, vertical directrix at a distance of 2 units to the right of the pole
hyperbola, vertical directrix at a distance of 2 units to the right of the pole

ellipse, vertical directrix at a distance of 2 units to the right of the pole

1 answer

To analyze the given polar equation \( r = \frac{4}{2 + 3 \sin \theta} \), we can convert it into a more recognizable form.

This equation resembles the general form of a conic section in polar coordinates:

\[ r = \frac{ed}{1 + e \sin \theta} \]

where \( e \) is the eccentricity and \( d \) is the distance from the pole to the directrix.

In our case, we need to manipulate the given equation to match this form:

\[ r = \frac{4}{2 + 3 \sin \theta} = \frac{4}{2} \cdot \frac{1}{1 + \frac{3}{2} \sin \theta} = 2 \cdot \frac{1}{1 + \frac{3}{2} \sin \theta} \]

This shows that:

  • \( e = \frac{3}{2} \) (the coefficient of \( \sin \theta \))
  • \( ed = 2 \) (from the \( r = \frac{ed}{1 + e \sin \theta} \) form)

Thus, we can find \( d \):

\[ d = \frac{ed}{e} = \frac{2}{\frac{3}{2}} = \frac{4}{3} \]

Since \( e = \frac{3}{2} > 1 \), this indicates that the curve represented by this equation is a hyperbola.

Moreover, the directrix is vertical since the conic form has \( \sin \theta \). Given the equation, we identify the directrix based on \( d \):

  • The horizontal directrix (due to \( \sin \theta \)) will be at a distance of \( \frac{4}{3} \) units above the pole.

Therefore, the correct description of the graph represented by the equation is:

hyperbola, horizontal directrix at a distance of \( \frac{4}{3} \) units above the pole.