06.09.2021 Views

A First Course in Linear Algebra, 2017a

A First Course in Linear Algebra, 2017a

A First Course in Linear Algebra, 2017a

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

438 Some Curvil<strong>in</strong>ear Coord<strong>in</strong>ate Systems<br />

♠<br />

Consider another example of construct<strong>in</strong>g a polar graph.<br />

Example 8.6: A Polar Graph<br />

Graph r = 1 + 2cosθ for θ ∈ [0,2π].<br />

Solution. The graph of the polar equation r = 1 + 2cosθ for θ ∈ [0,2π] is given as follows.<br />

y<br />

x<br />

To see the way this is graphed, consider the follow<strong>in</strong>g picture. <strong>First</strong> the <strong>in</strong>dicated po<strong>in</strong>ts were graphed<br />

and then the curve was drawn to connect the po<strong>in</strong>ts. When done by a computer, many more po<strong>in</strong>ts are<br />

used to create a more accurate picture.<br />

Consider first the follow<strong>in</strong>g table of po<strong>in</strong>ts.<br />

θ π/6<br />

√<br />

π/3 π/2 5π/6<br />

√<br />

π 4π/3 7π/6<br />

√<br />

5π/3<br />

r 3 + 1 2 1 1 − 3 −1 0 1 − 3 2<br />

Note how some entries <strong>in</strong> the table have r < 0. To graph these po<strong>in</strong>ts, simply move <strong>in</strong> the opposite

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!