Pre-Calculus: 1001 Practice Problems For Dummies (+ Free Online Practice)

You’ll work on graphing complex numbers. Polar coordinates are quite different from the usual (x, y) points on the Cartesian coordinate system. Polar coordinates bring together both angle measures and distances, all in one neat package. With the polar coordinate system, you can graph curves that resemble flowers and hearts and other elegant shapes.

You’ll work on complex numbers and polar coordinates in the following ways:

• Interpreting graphs of basic polar coordinates

• Graphing polar equations such as cardioids and lemniscates

When working with complex numbers and polar coordinates, some challenges will include the following:

• Moving in a counterclockwise direction when graphing polar coordinates

• Recognizing which ray to use when graphing negative and multiple angle measures

Practice problems

1. Identify the point on the polar coordinate plane. Give your answer in

form, where

is in radians.

Credit: Illustration by Thomson Digital

Answer: i301

The point is on the 2-unit ring, so the radius is 2. You measure the angle from the positive x-axis in a counterclockwise direction. Each ray represents 15 degrees, so this point is on the ray representing

The radius is 2, so the point is 2 units out from the origin.

2. Change the polar coordinates to rectangular coordinates.

Answer:

You find the x coordinate with

so

You find the y coordinate with

so

About This Article

About the book author:

Mary Jane Sterling is the author of Algebra I For Dummies, Algebra Workbook For Dummies, and many other For Dummies books. She taught at Bradley University in Peoria, Illinois for more than 30 years, teaching algebra, business calculus, geometry, and finite mathematics.