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12.06 Graphing polar equations

Lesson

When we have graphed rectangular equations in the past, we started by creating a table of values. We then plotted the points from the table and connected them with a continuous curve. We can approach graphing polar equations in the same way. This starts with understanding their coordinates and is best seen by looking at some examples.

Practice questions

QUESTION 1

Consider the point $\left(8,\frac{11\pi}{6}\right)$(8,11π6), in polar coordinates.

  1. This point is $\editable{}$ units away from the pole on a polar grid.

  2. What is the size of the angle that the point makes with the polar axis? Give your answer in radians.

  3. Which of the following shows the location of $\left(8,\frac{11\pi}{6}\right)$(8,11π6) on a polar grid?

    A polar coordinate grid with several blue points labeled from A to H. The grid has concentric circles increasing in radius at consistent intervals which represents the axes of the polar coordinate grid. The fifth circle is labeled $10$10 indicating that it is the 10th axis. Point $A$A is at $\left(8,\frac{\pi}{3}\right)$(8,π3); point $B$B is at $\left(8,\frac{\pi}{6}\right)$(8,π6); point $C$C is at $\left(8,\frac{11\pi}{6}\right)$(8,11π6); point $D$D is at $\left(8,\frac{5\pi}{3}\right)$(8,5π3); point $E$E is at $\left(4,\frac{\pi}{3}\right)$(4,π3); point $F$F is at $\left(4,\frac{\pi}{6}\right)$(4,π6); point $G$G is at $\left(4,\frac{11\pi}{6}\right)$(4,11π6); point $H$H is at $\left(4,\frac{5\pi}{3}\right)$(4,5π3). The coordinates of all points are not explicitly given in the image and should never be given as answer to any questions/prompts.

QUESTION 2

Convert the point $\left(9,5\right)$(9,5) from rectangular coordinates to polar coordinates $\left(r,\theta\right)$(r,θ), where $0\le\theta<2\pi$0θ<2π. Give each value correct to two decimal places.

QUESTION 3

Convert the point $\left(4,\left(-46\right)^\circ\right)$(4,(46)°) from polar coordinates to rectangular coordinates $\left(x,y\right)$(x,y). Give each value correct to two decimal places.

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