1.1 square roots of perfect squares math 90. for each shaded square: –what is its area? –write...
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1.1 Square Roots of Perfect Squares
Math 90
• For each shaded square:– What is its area?– Write this area as a product.– How can you use a square root to relate
the side length and area?
Calculate the Area:
Calculate the side length
For the area of each square in the table…• Write the area as a product.• Write the side length as a square root.
Squaring vs. Square Rooting• Squaring and square rooting are opposite, or inverse
operations.– Eg.
• When you take the square root of some fractions you will get a terminating decimal.
– Eg.
• These are all called RATIONAL numbers.
225
100
29 81 9 3
• When you take the square root of other fractions you will get a repeating decimal.– Eg.
• These are all called RATIONAL numbers
1
91 1
0.339
1.2 Square Roots of Non-Perfect Squares
d
Introduction...
• Many fractions and decimals are not perfect squares.
• A fraction or decimal that is not a perfect square is called a non-perfect square.– The square roots of these numbers do not
work out evenly!
• How can we estimate a square root of a decimal that is a non-perfect square?
Here are 2 strategies...
7.5
7.5
Ask yourself: “Which 2 perfect squares are
closest to 7.5?”
2 32.5
7.5 is closer to 9 than to 4, so is closer to 3 than to 2.
7.5
What would be a good approximation?
Strategy #2...
• Use a calculator! • But, of course, you must be able to do
both!
Example #1
• Determine an approximate value of each square root.
8
5close to 9
close to 4
8 3
5 2
What does this mean?
We call these 2 numbers
‘benchmarks’.
Example #2
• Determine an approximate value of each square root.
3
10
30.55
10
0.3
0.25 0.400.300.20 0.36
Of course, you can always use a calculator to CHECK
your answer!
Your benchmarks!
What’s the number?• Identify a decimal that has a square root
between 10 and 11.
120110100
If these are the square roots, where do we start?
121
1110
Mr. Pythagoras
• Junior High Math Applet
Remember, we can only use Pythagorean Theorem on RIGHT angle
triangles!
Practicing the Pythagorean Theorem
5 cm
First, ESTIMATE each missing side and then CHECK using your calculator.
8 cm
13 cm
7 cm
x
x
Applying the Pythagorean Theorem
The sloping face of this ramp needs to be covered with Astroturf.
a) Estimate the length of the ramp to the nearest 10th of a metre
b) Use a calculator to check your answer.
c) Calculate the area of Astroturf needed.
2.2 cm
6.5 cm
1.5 cm
Let’s quickly review what we’ve learned today...
• Explain the term non-perfect square.
• Name 3 perfect squares and 3 non-perfect squares between the numbers 0 and 10.
• Why might the square root shown on a calculator be an approximation?
Assignment Time!
• Complete the following questions in your notebook.
• Be prepared to discuss your answers in class.
• Show all of your work!