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Active Calculus

Section 9.5 Calculus in Polar Coordinates

Exercises Exercises

1.

(a) The Cartesian coordinates of a point are \((1,1).\)
(i) Find polar coordinates \((r,\theta)\) of the point, where \(r>0\) and \(0 \le \theta \lt 2\pi.\)
\(r =\)
\(\theta =\)
(ii) Find polar coordinates \((r,\theta)\) of the point, where \(r\lt 0\) and \(0 \le \theta \lt 2\pi.\)
\(r =\)
\(\theta =\)
(b) The Cartesian coordinates of a point are \((2\sqrt{3},-2).\)
(i) Find polar coordinates \((r,\theta)\) of the point, where \(r>0\) and \(0 \le \theta \lt 2\pi.\)
\(r =\)
\(\theta =\)
(ii) Find polar coordinates \((r,\theta)\) of the point, where \(r\lt 0\) and \(0 \le \theta \lt 2\pi.\)
\(r =\)
\(\theta =\)

2.

For each set of Polar coordinates, match the equivalent Cartesian coordinates.

3.

Find the equation in polar coordinates of the line through the origin with slope \(\frac1{5}\text{.}\)
\(\theta=\)

4.

Find the slope of the tangent line to the polar curve \(r=1/\theta\) at the point specified by \(\theta=\pi.\)
Slope =

5.

Find the equation (in terms of \(x\) and \(y\)) of the tangent line to the curve \(r=4\sin5\theta\) at \(\theta=\pi/4\text{.}\)
\(y =\)

6.

Find the area of the region bounded by the polar curve \(r = 9 e^ \theta\) , on the interval \(\frac{4}{9} \pi \leq \theta \leq 2 \pi\text{.}\)
Answer:

7.

Find the total area enclosed by the cardioid \(r=8-\cos\theta\) shown in the following figure:
Answer :

8.

Find the area of one leaf of the "four-petaled rose" \(r =9 \sin 2\theta\) shown in the following figure:
With \(r_0=9\)
Answer :

9.

Find the area lying outside \(r=4\sin\theta\) and inside \(r=2 + 2 \sin\theta\text{.}\)
Area =

10.

Find the exact length of the polar curve
\begin{equation*} r=3\sin(\theta),\;\;0 \le \theta \le \pi/3. \end{equation*}
Length =

11.

Find the length of the spiraling polar curve
\(r = 4 e^{6 \theta}\)
From 0 to \(2 \pi\) .
The length is
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