Texas Instruments TI-89 Manual Book page 408

Finding the
Minimum Surface
Area Analytically
Hint: Press ¸ to obtain
the exact result in symbolic
form. Press ¥ ¸ to
obtain the approximate
result in decimal form.
Perform the following steps to solve the problem analytically on the
Home screen.
1. Solve for and in terms of
x y
Enter:
solve( d (sa(x,y,v),x)=0 and
d (sa(x,y,v),y)=0,{x,y})
2. Find the minimum surface area
when the value of v
Enter:
300! v
Enter: sa(v^(1/3), v^(1/3),v)
.
v
equals 300.
Chapter 23: Activities 391