Determining max and min pts of a polar curve

In summary, the polar curve r = 3 + sin q can be graphed as an upside down heart or a circle with the y-axis passing through the middle. To find the maximum and minimum values of the curvature at points of this curve, one can either inspect the graph or use the equation r = 3 + sin q to find the angle at which the curvature is equal to zero. In order to plot these graphs in graphmatica, the equations r = 3 + sin t and x = 2sin t - sin(2t), y = -2cos t + cos(2t) {-pi,pi} can be used, and more information can be found by typing "parametric" in the index and
  • #1
KataKoniK
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Determine the maximum and minimum values of the curvature at points of the polar curve r = 3 + sin q.

I know that the polar curve, r = 3 + sin q is sort of similar to an upside down heart when graphed. However, I am not sure what to do when finding the maximum and minimum values of the curvature at points of r = 3 + sin q.

Thanks in advance.
 
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  • #2
KataKoniK said:
Determine the maximum and minimum values of the curvature at points of the polar curve r = 3 sin q.
...
You want to find the max and min values of the curve, rather than the curvature, yes?
The curvature is the rate at which the slope is changing.

KataKoniK said:
...
I know that the polar curve, r = 3 sin q is sort of similar to an upside down heart when graphed
...
Sorry, but the polar curve you gave is just a circle, sitting on top of the x-axis with the y-axis passing through the middle of it.
What you described sounds like an epi-cycloid.

KataKoniK said:
... However, I am not sure what to do when finding the maximum and minimum values of the curvature at points of r = 3 sin q.

Thanks in advance.
There are a couple of ways of doing this problem. You can just sketch, and label, the graph of the curve and simply state that, by inspection, from the Figure/sketch, the max and min points are such-and-such.

Or, you can use http://archives.math.utk.edu/visual.calculus/3/polar.1/.
Set dy/dx equal to zero and solve for the angle.
 

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  • #3
Thanks. btw, how did you plot those graphs in graphmatica?

edit - I also realized I made a typo with the equation. It's suppose to be r = 3 + sin q and not r = 3 sin q.
 
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  • #4
for the circle, just type in at the "function" window,

r = 3 + sin(t)

for the epi-cycloid, just type in at the "function" window,

x = 2sin(t) - sin(2t); y = -2cos(t) + cos(2t) {-pi,pi}

where the {-pi,pi}is the range.

If you hit F1 then type "parametric" in the index, then click on "Display", you'll get full info.
 

1. What is a polar curve?

A polar curve is a type of graph that represents a function in polar coordinates. It is formed by plotting points with polar coordinates (r, θ) on a polar axis system, where r represents the distance from the origin and θ represents the angle from the polar axis.

2. How do you determine the maximum and minimum points of a polar curve?

To determine the maximum and minimum points of a polar curve, you first need to convert the polar equation into rectangular form. Then, take the derivative of the function with respect to θ and set it equal to 0 to find the critical points. Finally, plug in the critical points into the original equation to find the maximum and minimum points.

3. Can a polar curve have more than one maximum or minimum point?

Yes, a polar curve can have multiple maximum and minimum points. This occurs when there are multiple critical points found when taking the derivative of the function. These points can also be found by graphing the polar curve and identifying the points with the highest and lowest values.

4. How do you graph a polar curve to determine the maximum and minimum points?

To graph a polar curve, you can plot points on a polar axis system and connect them to form a curve. Then, identify the points with the highest and lowest values to determine the maximum and minimum points. Alternatively, you can also use a graphing calculator or computer software to graph the polar curve and find the maximum and minimum points.

5. Can a polar curve have a maximum or minimum point at the origin?

Yes, a polar curve can have a maximum or minimum point at the origin. This occurs when the function has a vertical tangent line at the origin, where r = 0. In this case, the function has an extreme value at the origin, making it a maximum or minimum point on the polar curve.

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