Texas Instruments TITANIUM TI-89 - Manual (Page 751)

Activities 751
Finding the Minimum Surface Area Analytically Finding the Minimum Surface Area Analytically Finding the Minimum Surface Area Analytically Finding the Minimum Surface Area Analytically
Perform the following steps to solve the problem analytically on the Home screen.
2. Select the 3D Graph mode. Then enter
the function for z1(x,y) as shown in this
example with volume v=300 .
3. Set the Window variables to:
eye= [60,90,0]
x=
[0,15,15]
y= [0,15,15]
z= [260,300]
ncontour= [5]
4. Graph the function and use Trace to go to
the point close to the minimum value of
the surface area function.
1. Solve for x and y in terms of v .
Enter: solve(d(sa(x,y,v),x)=0 and
d(sa(x,y,v),y)=0,{x,y})