14. Chapter 2: Solving a Problem To find the z-coordinate of the starting point: Evaluate the function representing the hill at the x-and y-values representing the starting point(x1, y1). At the prompt, enter the following and press ENTER. 1:=eval(f,{x=x1,y=y1}); 2.145631453) is an approximation of the skiers starting pont,21 The numerical result{x1=-.8526100199,y1=-1.755220040 Finding the path down Before you find the path take a look at the level curves of the hill to get an idea of the skier's path To plot the level curves The contourplot command with five contours suggests an interesting shape, as shown in Figure 2-B. At the prompt, enter the following command and press ENTER. contourplot(f, X=-2 y=-3.l, contours=5, filled=true) contourplot(f, x=-2.1, ye-3. 1, contours=5, filled-true): a Figure 2-B Level curves of the hill14 • Chapter 2: Solving a Problem To find the -coordinate of the starting point: • Evaluate the function representing the hill at the 3 and %3values representing the starting point ()%)). At the prompt, enter the following and press ENTER. :)&'/"1')%'%)2$ The numerical result {)'3 67,5))44%)'3) ;77,,-:)' , )-75()-7(2 is an approximation of the skier’s starting point. Finding the path down Before you find the path, take a look at the level curves of the hill to get an idea of the skier’s path. To plot the level curves: • The   command with five contours suggests an interesting shape, as shown in Figure 2-B. At the prompt, enter the following command and press ENTER.   "'−, )%'−( ) 
'7"' $ Figure 2-B Level curves of the hill