Transcript
  • 8/7/2019 Lesson 24 Pythagorean Theorem

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    DO NOW!

    4

    2

    +5

    2

    =c

    2

    Solve.Evaluate.

    6

    2

    +7

    2

    3

    2

    +8

    2

    =c

    2

    7

    2

    +10

    2

    =c

    2

    11

    2

    +6

    2

    =c

    2

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    LESSON 24: PYTHAGOREAN THEOREM

    STANDARDS: 7.G.5, 7.G.6, 7.G.8, and 7.G.9

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    Can you identify all parts of a right triangle?

    leg

    leg

    right angle

    hypotenuse

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    Word Description

    The sides of a right triangle thatshare the 90 degree angle.

    The side of a right triangle that isopposite the 90 degree angle.

    The sum of the squares of the legs isequal to the square of thehypotenuse.

    Legs

    Pythagorean

    Theorem

    Hypotenuse

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    Identify the legs and the hypotenuse

    hypotenuselegs

    a

    cb

    b

    a

    c

    c

    ba

    cb

    a

    cba cba

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    What do you notice?

    Find the area of each square.

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    Can you arrange the blue and pink squares inside the yellow square?

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    The Pythagorean Theorem

    a2

    + b2

    = c2

    TOUCH

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    In right triangles,

    the square of thelength of thehypotenuse is

    equal to the sum ofthe squares of thelengths of the legs.

    a2

    + b2

    = c2

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    Identify the hypotenuse in each triangle

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    What is the Pythagorean Theorem?

    Label the following triangle, according the theorem.

    What is the equation?

    hypotenuse

    bc

    leg

    lega

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    What is Pythagorean Theorem?

    How do we use Pythagorean Theorem?

    Pythagorean Theorem is a rule that helps findthe distance or measure of one side of a right

    triangle when two measures are known.

    Substitute the measures into thePythagorean Theorem,use Algebra to solve the equation.

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    For which triangles does the Pythagorean theorem apply?

    4

    1 2

    3

    5

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    Using the Pythagorean Theorem

    3

    4

    Example 1:Find the unknown measurement. Refer to the diagram!

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    Example 2:Find the unknown measurement.Refer to the diagram.

    15 12

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    What happens when you try to find thesquare root of a 'non-perfect' square?

    For example, what is the square root of 41?

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    5cm

    6 cm

    c

    Step 1:

    a = 5b = 6c = x

    Step 2:

    a2

    + b2

    = c2

    52

    + 62

    = x2

    25 + 36 = x2

    61 = x2

    Using the Pythagorean theorem, it is possible, knowing thelength of sides a and b, to figure out the length of side c.

    Step 3

    61 = x2

    61 = x

    7.81 = xx = c =7.81 cm

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    1.

    2cm

    2 cm

    2.

    2cm

    6 cm

    ___ cm

    Find the missing lengths!

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    a b c a2 b2 c2 a2+b

    5 12 13 25 144 169 169

    8 15 17 64 225 289 289

    10 6.3 12 100 39.69 144 139.69

    10 6 11.3 100 36 127.69 136

    6 8 10 36 64 100 100

    Copy and complete!

    NOTRIGHTTRIANGLES

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    1.

    4cm

    1 cm

    2.

    3cm

    5 cm

    ___ cm___ cm

    3.

    1

    cm

    1 cm

    4.

    2cm

    6 cm

    ___ cm___ cm

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    One end of a ladder is placed 7 feet from a a house.The other of the ladder reaches 20 feet up the side ofthe house. How long is the ladder?

    Place all items in the proper place on the houseaccording to the story above.

    20 ft

    7 ft

    ?

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    12 ft

    43 ft

    How high off the ground is the owl?

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    LEARNING LOG - 7.G.8 - NickiNicki is unsure how to find the missing value. Can youhelp her? Explain your reasoning and show all work.

    3cm ___ cm

    8 cm

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    a = 8

    c = 12b = 8 b = 12

    c = 13

    a = 5

    Considering the three side measurements (a, b, and c), which of the followingtwo triangles is a right triangle?

    Triangle 1 Triangle 2

    A right triangle can be found whenever the Pythagorean Theorem is true.

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    Which of these triangles are right triangles?

    11.3 yards

    10y

    ards

    6yard

    s

    8 meters

    10m

    eters

    6me

    ters

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    LEARNING LOG - 7.G.9 - Is it a Right Triangle?

    5

    inc

    hes

    4inches

    6in

    ches

    Is this a right triangle? How can you tell?Explain and show proof.

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    How do we find a missing leg?!

    3

    5

    b

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    a2

    + b2

    = c2

    82

    + 62

    = c2

    64 + 36 = 100100 = c

    2

    c = 10

    a2

    + b2

    = c2

    52

    + y2

    = 82

    25 + y

    2

    = 64

    y2

    = 39

    Length of the hypotenuse Length of a leg

    6

    8c

    5

    8

    y

    Find the missing lengths


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