Chapter 1: Number Sense Section 3: Real Numbers
Topics In Algebra 1 © 2001 Texas Instruments Teacher Notes 1-33
³
Try-It!
é
on Your TI
.
73 or TI
.
83 Plus
Tell students to:
•
Use the Pythagorean theorem to draw a triangle whose two legs = 1 unit and whose
hypotenuse =
À
2
units.
•
Shade in the area on the Geoboard screen on the worksheets.
•
Go through the keystroke example to:
- Find the calculator decimal approximation for
À
2
.
- Understand how the calculator approximates numbers.
- Understand that they must be conscientious about the mathematics involved.
Word Problem: Missy’s Garden
Remind students to:
•
Use the Pythagorean theorem to find the third side of the garden and then the perimeter.
•
Set the decimal mode notation (
.
) to
Float
and then to
1
(answer rounded to tenths), so
they can see how the calculator displays answers.
1. Exact perimeter: 1 + 2 +
À
5
meters
2. Length of fencing rounded to tenths: 5.2 meters
Note:
The number rounds down. This is mathematically correct, but impractical in the real world, where Missy would need to purchase 5.3
meters in order to fence the garden. You may want to discuss meaningful interpretation of word problems with the students.
Word Problem: Jose and Maria’s Backyard Pool
If necessary, review the formulas for area of a square and area of a circle. They are shown on the
worksheet.
Covering material left over:
1. Exact: Area of square—area of circle
= (3.5)
2
N
p
(3.5/2)
2
= 12.25
N
3.0625
p
square meters
2. Approximate:
2.629
square meters
(3
decimal places; use
Float=3
)
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