About the Cover

The cable car railway system was invented specifically to operate on San Francisco's famous hills. Every cable car is pulled along its track by an underground cable. The cable is gripped with a viselike mechanism that is operated by the driver using a grip lever in the front of the car. In Chapter 4, you will learn about slopes like the slope of a hill.

About the Graphics
Twisted torus. Created with Mathematica. A torus with rose-shaped cross section is constructed. Then the cross section is rotated around its center as it moves along a circle to form a twisted torus. For more information, and for programs to construct such graphics, see: www.wolfram.com/r/textbook.