(adsbygoogle = window.adsbygoogle || []).push({}); Equation of tangent line (rec. form) to a polar curve!!

1. The problem statement, all variables and given/known data

Quesiton:

Find the rectangular form of the equation of the tangent line to the polar curve r=cos^3(theta) at the point corresponding to theta=pi/4

2. Relevant equations

3. The attempt at a solution

How to do that?

I mean finding it in RECTANGULAR FORM !

i know that

[tex]\frac{dy}{dx}=\frac{\frac{dr}{d\theta} sin(\theta)+rcos(\theta)}{\frac{dr}{d\theta} cos(\theta) - r sin(\theta)}[/tex]

I will calculate dy/dx at theta=pi/4 , and this is easy ..

The problem here is that, how can I find the equation of the tangent line in RECATNGULAR FORM ??

The equation of the tangent line is :

y-y1=m(x-x1)

m = the slope , and this one will be calculated by using the formula ..

but what about x1 and y1?

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# Homework Help: Equation of tangent line (rec. form) to a polar curve

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