What is the graph of a polar curve with specific r and theta values?

In summary, the polar curve described has four sections where r decreases as theta increases: from (4,0) to (0,2), from (0,2) to (0,0), from (0,0) to (0,-1), and from (0,-1) to (-3,0). The graph of the curve can be refined to more accurately show the decrease in r at certain points. There is no need to convert to rectangular coordinates for this type of problem.
  • #1
ThirdEyeBlind
12
0

Homework Statement


Sketch a graph of the polar curve whose points satisfy the following:

As theta increases from 0 to pi/2, r decreases from 4 to 2.
As theta increases from pi/2 to pi, r decreases from 2 to 0.
As theta increases from pi to 3pi/2, r decreases from 0 to -1.
As theta increases from 3pi/2 to 2pi, r decreases from -1 to -3.

Homework Equations


The Attempt at a Solution


First, I converted the points from polar to cartesian and got the following:
(r, theta) -> (x,y)
(4, 0) -> (4, 0)
(2, pi/2) -> (0, 2)
(0, pi) -> (0, 0)
(-1, 3pi/2) ->(0, 1)
(-3, 2pi) -> (-3, 0)Then, I graphed the points in order and got:
04wf4.jpg


I think this is right, I am just looking for someone to look over my work as I have to turn this in.

ThanksEdit: Whoops, I meant to post this in the Calculus & Beyond forum. If someone could move it there, I would appreciate it.
 
Last edited:
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  • #2
It looks fine to me.

Actually, you might want to refine the curves a bit. Depending on how picky the grader is, he or she might argue that, for instance, r isn't decreasing as you near the point (0,2) from the right.
 
  • #3
Also, I would suggest that for such problems, there is no need to convert to rectangular coordinates. Just draw lines at a few theta values and mark off r values that satisfy your conditions.
 

Related to What is the graph of a polar curve with specific r and theta values?

What are polar coordinates?

Polar coordinates are a way of representing points in a two-dimensional space using a distance from the origin and an angle from a reference line.

How do you convert between polar and rectangular coordinates?

To convert from polar coordinates (r,θ) to rectangular coordinates (x,y), you can use the formulas x = rcosθ and y = rsinθ. To convert from rectangular coordinates (x,y) to polar coordinates (r,θ), you can use the formulas r = √(x^2 + y^2) and θ = arctan(y/x).

What are some common equations in polar coordinates?

Some common equations in polar coordinates include circles (r = a), lines (θ = constant), and cardioids (r = a + bcosθ).

How do you graph polar equations?

To graph polar equations, you can plot points by substituting different values for θ, and then connecting the points to create a curve. You can also use a calculator or graphing software to plot the equation.

How are derivatives and integrals calculated in polar coordinates?

In polar coordinates, the derivative of a function is calculated using the chain rule and the derivative of the polar coordinate equations. The integral of a function over a polar region is calculated using the formula ∫∫f(r,θ)rdrdθ.

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