Economy Of Materials (Cross-Sectional Area) - Casio fx-7400G PLUS Booklet

AR-1 Economy of Materials (Cross-sectional Area)
Exercise 1
Economy of Materials
You want to form a piece of sheet metal to make a shape like
the one shown in the illustration nearby, in order to create the
largest possible cross-sectional area. Draw a graph to deter-
mine the distance from the edge of the sheet metal where it
should be bent in order to produce the largest possible area
using a piece of sheet metal that is 20 cm wide.
Explanation
When the distance from the edge of the sheet metal to the bend is
y
sectional area is
y x
= (20 – 2
y
Differentiating by
o = 20 – 4
y
Determining the value of
x
4 (5 – ) = 0
This means that when
at the two points that are 5 cm from either of its sides.
The following graph shows the relationship between the bend points and cross-sectional area.
The following is the operation required on a graphic scientific calculator, which also makes
the calculation easier to understand.
Operation
•
Expression Input
From the Main Menu, enter the GRAPH Mode.
After making sure the cursor is located at Y1:, perform
the following key operation.
T-
20
y
(cm 2 ), can be expressed by the following expression.
(0 
x x x
) = 20 – 2 2
x
gives us:
x x
= 4 (5 – )
o= 0 produces the following:
x when y
x
= 5
x
= 5, the value of
y
50
0
Txw
2
JIKKYO SHUPPAN CO., LTD.: SHIN KOGYO SURI
10)
x
y
is at its maximum, so the sheet metal should be bent
(0<x<10)
x
5 10
y = 20x –
x
2 2
– 49 –
(NEW EDITION)
Cross-sectional area
x
x
Unit: cm
x
(cm) and the cross-