How Do You Convert These Polar Equations to Rectangular Form?

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Discussion Overview

The discussion revolves around converting polar equations into rectangular form, specifically focusing on the equations r = 2 sin(3θ) and r = 6 / (2 - 3 sin(θ)). Participants seek assistance and clarification on the conversion process, including the use of trigonometric identities and formulas.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant requests help with converting the polar equations into rectangular form and asks for a step-by-step explanation.
  • Another participant suggests starting with the equation r = 2 sin(3θ) and manipulating it using the identity r^2 = 2r sin(3θ).
  • A participant mentions that their instruction has only covered double angle formulas, indicating a limitation in their knowledge of trigonometric identities.
  • One participant encourages another to use the sum of angles formula for sine to expand sin(3θ) as sin(θ + 2θ).
  • A participant presents an intermediate result involving r^2 and attempts to factor out sin(θ) cos(θ), questioning whether to further expand the equation.
  • Another participant corrects the previous approach by stating the correct expansion of sin(3θ) as 3 sin(θ) - 4 sin³(θ) and provides the corresponding equation for r².

Areas of Agreement / Disagreement

The discussion features differing levels of understanding regarding trigonometric identities, with some participants providing corrections and alternative approaches. No consensus is reached on the best method for conversion, and uncertainty remains about the steps to take next.

Contextual Notes

Participants express varying familiarity with trigonometric identities, which may affect their ability to follow the discussion. There are unresolved mathematical steps and assumptions regarding the application of formulas.

Dooh
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Can someone help me with these problems? It's been bugging me i can't seem to solve it.

Lets assume T = theta

I can't seem to find a way to convert these polar equations into rectangular form.

r = 2 sin 3T

r = 6 / 2 - 3 sinT

If possible, can someone help me with this and list it in a step-by-step fashion so i can see how you get the answer. Thanks.
 
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[tex]r = 2 \sin (3 \theta)[/tex]

[tex]r^2 = 2r \sin (3 \theta)[/tex]

then try the triple angle formulas to reduce [itex]\sin (3 \theta)[/itex]
 
Sorry but the furthest that our teacher had taught us in the double angle formula.
 
It's not hard. Why don't you try it?

[tex]\sin (3 \theta) = \sin (\theta + 2 \theta)[/tex]

Use the sum of angles for the sin

[tex]\sin (\alpha + \beta) = \sin \alpha cos \beta + \cos \alpha \sin \beta[/tex]
 
Ok, so i got:


[tex]r^2 = 2r (\sin \theta \cos 2 \theta + \cos \theta \sin 2 \theta )[/tex]

can i take out the [tex]\sin \theta \cos \theta[/tex]

and get

[tex]r^2 = 2r \sin \theta \cos \theta (\cos \theta + \sin \theta )[/tex]

or should i further expand the equation?
 
No that's wrong it will be

[tex]\sin (3 \theta) = 3 \sin \theta - 4 \sin^{3} \theta[/tex]

thus

[tex]r^2 = 2r (3 \sin \theta - 4 \sin^{3} \theta)[/tex]
 

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