<< Chapter < Page Chapter >> Page >

How are the polar axes different from the x - and y -axes of the Cartesian plane?

Got questions? Get instant answers now!

Explain how polar coordinates are graphed.

Determine θ for the point, then move r units from the pole to plot the point. If r is negative, move r units from the pole in the opposite direction but along the same angle. The point is a distance of r away from the origin at an angle of θ from the polar axis.

Got questions? Get instant answers now!

How are the points ( 3 , π 2 ) and ( 3 , π 2 ) related?

Got questions? Get instant answers now!

Explain why the points ( 3 , π 2 ) and ( 3 , π 2 ) are the same.

The point ( 3 , π 2 ) has a positive angle but a negative radius and is plotted by moving to an angle of π 2 and then moving 3 units in the negative direction. This places the point 3 units down the negative y -axis. The point ( 3 , π 2 ) has a negative angle and a positive radius and is plotted by first moving to an angle of π 2 and then moving 3 units down, which is the positive direction for a negative angle. The point is also 3 units down the negative y -axis.

Got questions? Get instant answers now!

Algebraic

For the following exercises, convert the given polar coordinates to Cartesian coordinates with r > 0 and 0 θ 2 π . Remember to consider the quadrant in which the given point is located when determining θ for the point.

( 5 , π )

( 5 , 0 )

Got questions? Get instant answers now!

( 3 , π 6 )

( 3 3 2 , 3 2 )

Got questions? Get instant answers now!

For the following exercises, convert the given Cartesian coordinates to polar coordinates with r > 0 , 0 θ < 2 π . Remember to consider the quadrant in which the given point is located.

( 4 , 2 )

( 2 5 ,   0.464 )

Got questions? Get instant answers now!

( 3 , −5 )

( 34 , 5.253 )

Got questions? Get instant answers now!

( 8 , 8 )

( 8 2 , π 4 )

Got questions? Get instant answers now!

For the following exercises, convert the given Cartesian equation to a polar equation.

y = 2 x 4

r = s i n θ 2 c o s 4 θ 3

Got questions? Get instant answers now!

x 2 + y 2 = 3 x

r = 3 cos θ

Got questions? Get instant answers now!

x 2 y 2 = 3 y

r = 3 sin θ cos ( 2 θ )

Got questions? Get instant answers now!

x 2 = 9 y

r = 9 sin θ cos 2 θ

Got questions? Get instant answers now!

9 x y = 1

r = 1 9 cos θ sin θ

Got questions? Get instant answers now!

For the following exercises, convert the given polar equation to a Cartesian equation. Write in the standard form of a conic if possible, and identify the conic section represented.

r = 4 cos θ

x 2 + y 2 = 4 x or ( x 2 ) 2 4 + y 2 4 = 1 ; circle

Got questions? Get instant answers now!

r = 4 sin θ + 7 cos θ

Got questions? Get instant answers now!

r = 6 cos θ + 3 sin θ

3 y + x = 6 ; line

Got questions? Get instant answers now!

r = 3 csc θ

y = 3 ; line

Got questions? Get instant answers now!

r 2 = 4 sec θ csc θ

x y = 4 ; hyperbola

Got questions? Get instant answers now!

r 2 = 4

x 2 + y 2 = 4 ; circle

Got questions? Get instant answers now!

r = 1 4 cos θ 3 sin θ

Got questions? Get instant answers now!

r = 3 cos θ 5 sin θ

x 5 y = 3 ; line

Got questions? Get instant answers now!

Graphical

For the following exercises, find the polar coordinates of the point.

For the following exercises, plot the points.

For the following exercises, convert the equation from rectangular to polar form and graph on the polar axis.

5 x y = 6

r = 6 5 cos θ sin θ

Plot of given line in the polar coordinate grid
Got questions? Get instant answers now!

x 2 + ( y 1 ) 2 = 1

r = 2 sin θ

Plot of given circle in the polar coordinate grid
Got questions? Get instant answers now!

( x + 2 ) 2 + ( y + 3 ) 2 = 13

Got questions? Get instant answers now!

x 2 + y 2 = 3 x

r = 3 cos θ

Plot of given circle in the polar coordinate grid.
Got questions? Get instant answers now!

For the following exercises, convert the equation from polar to rectangular form and graph on the rectangular plane.

r = 4

x 2 + y 2 = 16

Plot of circle with radius 4 centered at the origin in the rectangular coordinates grid.
Got questions? Get instant answers now!

r = −10 sin θ

x 2 + ( y + 5 ) 2 = 25

Plot of circle with radius 5 centered at (0,-5).
Got questions? Get instant answers now!

Technology

Use a graphing calculator to find the rectangular coordinates of ( 2 , π 5 ) . Round to the nearest thousandth.

( 1.618 , 1.176 )

Got questions? Get instant answers now!

Use a graphing calculator to find the rectangular coordinates of ( 3 , 3 π 7 ) . Round to the nearest thousandth.

Got questions? Get instant answers now!

Use a graphing calculator to find the polar coordinates of ( 7 , 8 ) in degrees. Round to the nearest thousandth.

( 10.630 , 131.186° )

Got questions? Get instant answers now!

Use a graphing calculator to find the polar coordinates of ( 3 , 4 ) in degrees. Round to the nearest hundredth.

Got questions? Get instant answers now!

Use a graphing calculator to find the polar coordinates of ( 2 , 0 ) in radians. Round to the nearest hundredth.

( 2 , 3.14 ) o r ( 2 , π )

Got questions? Get instant answers now!

Extensions

Describe the graph of r = a sec θ ; a > 0.

Got questions? Get instant answers now!

Describe the graph of r = a sec θ ; a < 0.

A vertical line with a units left of the y -axis. 

Got questions? Get instant answers now!

Describe the graph of r = a csc θ ; a > 0.

Got questions? Get instant answers now!

Describe the graph of r = a csc θ ; a < 0.

A horizontal line with a units below the x -axis.

Got questions? Get instant answers now!

What polar equations will give an oblique line?

Got questions? Get instant answers now!

For the following exercise, graph the polar inequality.

θ = π 4 , r 2

Graph of ray starting at (2, pi/4) and extending in a positive direction along pi/4 - polar coordinate grid.
Got questions? Get instant answers now!

θ = π 4 , r −3

Got questions? Get instant answers now!

0 θ π 3 , r < 2

Graph of the shaded region 0 to pi/3 from r=0 to 2 with the edge not included (dotted line) - polar coordinate grid
Got questions? Get instant answers now!

π 6 < θ π 3 , 3 < r < 2

Got questions? Get instant answers now!

Questions & Answers

What are types of cell
Nansoh Reply
how can I get this book
Gatyin Reply
what is lump
Chineye Reply
what is cell
Maluak Reply
what is biology
Maluak
what's cornea?
Majak Reply
what are cell
Achol
Explain the following terms . (1) Abiotic factors in an ecosystem
Nomai Reply
Abiotic factors are non living components of ecosystem.These include physical and chemical elements like temperature,light,water,soil,air quality and oxygen etc
Qasim
what is biology
daniel Reply
what is diffusion
Emmanuel Reply
passive process of transport of low-molecular weight material according to its concentration gradient
AI-Robot
what is production?
Catherine
Pathogens and diseases
how did the oxygen help a human being
Achol Reply
how did the nutrition help the plants
Achol Reply
Biology is a branch of Natural science which deals/About living Organism.
Ahmedin Reply
what is phylogeny
Odigie Reply
evolutionary history and relationship of an organism or group of organisms
AI-Robot
ok
Deng
what is biology
Hajah Reply
cell is the smallest unit of the humanity biologically
Abraham
ok
Achol
what is biology
Victoria Reply
what is biology
Abraham
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply
Practice Key Terms 3

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Algebra and trigonometry. OpenStax CNX. Nov 14, 2016 Download for free at https://legacy.cnx.org/content/col11758/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Algebra and trigonometry' conversation and receive update notifications?

Ask