Texas Instruments PLUS TI-89 - Manual (Page 408)

Chapter 23: Activities 391
23ACTS.DOC TI-89/TI-92 Plus: Activities (English) Susan Gullord Revised: 02/23/01 1:24 PM Printed: 02/23/01 2:20 PM Page 391 of 26
Perform the following steps to solve the problem analytically on the
Home screen.
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})
2. Find the minimum surface area
when the value of v equals 300.
Enter: 300 ! v
Enter: sa(v^(1/3), v^(1/3),v)
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.