Further Maths - Polar Coordinates


Flashcards

What is the $y = x$ equivalent for polar coordinates?


\[r = \theta\]

What is $x$ in terms of $r$ and $\theta$ for polar coordinates?


\[x = r\cos\theta\]

What is $y$ in terms of $r$ and $\theta$ for polar coordinates?


\[y = r\sin\theta\]

What is $r$ in terms of $x$ and $y$ for polar coordinates?


\[r = \sqrt{x^2 + y^2}\]

What is $\theta$ in terms of $x$ and $y$?


\[\tan^{-1}\left(\frac{x}{y}\right)\]

2021-11-15

$r = a\cos n\theta$

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\[r = a\cos\theta\]

What does this polar graph look like??

PHOTO ACOS1

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\[r = a\cos\theta\]

How would you describe IN WORDS what this look like?? A circle along the $x$-axis starting at the origin and ending after a diameter $a$ long.

\[r = a\cos\theta\]

What does this polar graph look like?


PHOTO ACOS1

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\[r = a\cos2\theta\]

What does this polar graph look like??

PHOTO ACOS2
\[r = a\cos\theta\]

How would you describe IN WORDS what this look like?


A circle along the $x$-axis starting at the origin and ending after a diameter $a$ long.

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\[r = a\cos3\theta\]

What does this polar graph look like??

PHOTO ACOS3

PHOTO ACOS1 What is the general polar equation for curves that look like this?


\[r = a\cos\theta\]

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\[r = a\cos4\theta\]

What does this polar graph look like??

PHOTO ACOS4
\[r = a\cos2\theta\]

What does this polar graph look like?


PHOTO ACOS2

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\[r = a\cos5\theta\]

What does this polar graph look like??

PHOTO ACOS5

PHOTO ACOS2 What is the general polar equation for curves that look like this?


\[r = a\cos2\theta\]

$r = a\sin n\theta$

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\[r = a\sin\theta\]

What does this polar graph look like??

PHOTO ASIN1

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\[r = a\sin\theta\]

How would you describe IN WORDS what this look like?? A circle along the $y$-axis starting at the origin and ending after a diameter $a$ long.

\[r = a\cos3\theta\]

What does this polar graph look like?


PHOTO ACOS3

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\[r = a\sin2\theta\]

What does this polar graph look like??

PHOTO ASIN2

PHOTO ACOS3 What is the general polar equation for curves that look like this?


\[r = a\cos3\theta\]

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\[r = a\sin3\theta\]

What does this polar graph look like??

PHOTO ASIN3
\[r = a\cos4\theta\]

What does this polar graph look like?


PHOTO ACOS4

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\[r = a\sin4\theta\]

What does this polar graph look like??

PHOTO ASIN4

PHOTO ACOS4 What is the general polar equation for curves that look like this?


\[r = a\cos4\theta\]

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\[r = a\sin5\theta\]

What does this polar graph look like??

PHOTO ASIN5
\[r = a\cos5\theta\]

What does this polar graph look like?


PHOTO ACOS5

PHOTO ACOS5 What is the general polar equation for curves that look like this?


\[r = a\cos5\theta\]
\[r = a\sin\theta\]

What does this polar graph look like?


PHOTO ASIN1

Cardioids

\[r = a\sin\theta\]

How would you describe IN WORDS what this look like?


A circle along the $y$-axis starting at the origin and ending after a diameter $a$ long.

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\[r = a + b\cos\theta\]

What does this polar graph look like, for $a = \vert b \vert $??

PHOTO ABCOS POINT

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\[r = a + b\cos\theta\]

What does this polar graph look like, for $a > \vert b \vert $??

PHOTO ABCOS BUMP

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\[r = a + b\sin\theta\]

What does this polar graph look like, for $a = \vert b \vert $??

PHOTO ABSIN POINT

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\[r = a + b\sin\theta\]

What does this polar graph look like, for $a > \vert b \vert $??

PHOTO ABSIN BUMP

Integration

Given a polar equation
\[r = ...\]

what is the formula for the area between angles $\alpha$ and $\beta$??

\[\frac{1}{2} \int^\alpha_\beta r^2 d\theta\]
Where does the polar integration formula
\[\frac{1}{2} \int^\alpha _ \beta r^2 d\theta\]

come from?? The formula for arc area, $\frac{1}{2}r^2\theta$

PHOTO ASIN1 What is the general polar equation for curves that look like this?


\[r = a\sin\theta\]

2021-11-17

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\[x = r\cos\theta\] \[y = r\sin\theta\]

Given that $r = \cos\theta$ what is the parametric form of the polar equation with parameter $\theta$??

\[(r\cos^2\theta, r\cos\theta\sin\theta)\]
For
\[r = f(\theta)\]

what is the formula for $x$??

\[x = f(\theta)\cos\theta\]
For
\[r = f(\theta)\]

what is the formula for $y$??

\[y = f(\theta)\sin\theta\]
If
\[\frac{\text{d}x}{\text{d}\theta} = 0\]

what is true about a polar curve for that value of $\theta$?? It is perpendicular to the initial line ($\theta = 0$).

If
\[\frac{\text{d}y}{\text{d}\theta} = 0\]

what is true about a polar curve for that value of $\theta$?? It is parallel to the initial line ($\theta = 0$).

\[r = a\sin2\theta\]

What does this polar graph look like?


PHOTO ASIN2

PHOTO ASIN2 What is the general polar equation for curves that look like this?


\[r = a\sin2\theta\]
\[r = a\sin3\theta\]

What does this polar graph look like?


PHOTO ASIN3




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