Jadonna Brewton

Fall 2000

Assignment #11

Problem # 2


r = 2a sin (kq) + b

(b is even)


(Click on the picture to see a moving graph that shows values of k from -6 to 6.)


We can classify the graphs into three groups:

1. Single roses with closed petals that converge at the origin. This occurs when b = 0 and when b = 2a. The radius of the rose is given by r = 2a + b. When b = 0, there are 2k petals. When b = 2a, there are only k petals.

(graphs in black and green).

2. Double roses composed of major and minor petals. This occurs when b < 2a. There are two radii to consider: the radius of the (1) major rose is given by r = 2a + b. (2) the minor rose is given by r = 2a - b. There are k major petals and k minor petals. There are a total of 2k petals.

(graphs in purple, red, and blue)

3. Open-petaled roses with an opening or core in the center. This occurs when b > 2a. There are two radii to consider: the radius of the (1) rose is given by r = 2a + b. (2) the core is given by r = 2a - b. There are k petals.

(graphs in cyan and yellow)

 

NOTE: The graphs of the equations with negative values of b are simply reflections about the y-axis. In cases where the radius was r = 2a + b in a positive b graph, the radius for a negative b graph has a radius of r = 2a - b. And in cases where the radius was r = 2a - b in a positive b graph, the radius for a negative b graph has a rdius of r = 2a + b.

Also, recall that if a or k (but not both) is negative, the graph is reflected about the x-axis. If BOTH a and k are negative, then the graph is the same as if both were positive.


Single Roses

(with circles to display radii.)

 

 

return


Double Roses

(with circles to display radii of inner and outer roses)

 

return

 


Open-Petaled Roses

(with circles to display radii of rose and opening, or core.)

 

return


 

 

 

Other equations in write-up # 11

OTHER WRITE-UPS

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