10.3: Polar functions* Learning Goals: Graph using polar form Convert polar coordinates to rectangular and vice versa Calculus of polar forms *BC Calculus Only ©2008 Roy L Gover (www.mrgover.com)
Definition A Polar Coordinate System is a method of locating a point (r, ) in a plane where r is a distance from a point called the pole directed at an angle θ measured counterclockwise from a polar axis.
Example r=10 Pole Polar Axis Polar Grid (r,θ )=
Example Find the polar coordinates: (r,θ )=
Example Find the polar coordinates: (r,θ )=
Example Graph: r=6
Example Graph: θ=
Some Classic Polar Graphs Example Some Classic Polar Graphs 8 petal rose
Some Classic Polar Graphs Example Some Classic Polar Graphs limacon
Some Classic Polar Graphs Example Some Classic Polar Graphs Spiral of Archimedes
Try This Use your graphing calculator to graph CARDIOID MODE POL Y=
Important Idea 8 4 petals Polar Roses
Important Idea 10 8 petals Polar Roses
Try This Name the angle in rads? Polar Roses
Try This Name the angle in rads? Polar Roses
Important Idea What do you observe about the number of petals?
Try This Describe what you would do to find the angle.
Try This Find the angle.
Important Idea Polar coordinates are related to rectangular coordinates as follows: r y θ x
Try This Change the polar coordinates to rectangular coordinates
Try This Change the rectangular coordinates to polar coordinates
Example Change the polar relation to a rectangular (cartesian) relation.
Important Idea The slope of the tangent line (derivative-rate of change) to the graph of at the point is: Remember:
Example Find the slope of at and use it to find the equation of the tangent line. Demana text ex 5 p.552
Try This Use the nDerive feature of your calculator to find the slope of the graph of the polar curve at Hint: find -.667
Analysis S r in radians Area Formula
Analysis Find the area from 0 to Area1=
Analysis Find the area from 0 to Area2=
Analysis Find the area from 0 to Area3=
Analysis Find the area from 0 to Riemann Sum for total area
Analysis Find the area from 0 to
Example Find the area enclosed by Demana Study Guide ex 6. p173
Try This Find the area of the region bounded by 703/10 18.850 sq u
Set up the integral to find the shaded area. Try This Set up the integral to find the shaded area. Hint: solve for when r=0 [PI/2,5PI/6]
Find the exact area of one petal of Try This Hint: 703/4 sq. units
Lesson Close This lesson completes the curriculum for BC Calculus. The topics I have taught have included everything in the College Board syllabus for BC Calculus.