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9.01 Distance and the Pythagorean theorem

Adaptive
Worksheet
What do you remember?
1

For each of the following right triangles:

i

Determine AB.

ii

Determine BC.

iii

Using the Pythagorean theorem, calculate AC, rounding your answer to two decimal places if necessary.

a
0
1
2
3
4
5
6
7
x
1
2
3
4
5
6
7
y
b
-4
-3
-2
-1
1
2
3
4
x
-1
1
2
3
4
5
6
y
2

For each of the following coordinate planes:

i
Copy the coordinate plane and draw a right triangle with \overline{AC} as the hypotenuse.
ii
Label the shorter two sides with the measure of their lengths.
iii
Use the Pythagorean theorem to find the distance between A and C, round your answer to one decimal place if necessary.
a
A = \left(0, 0\right), C = \left(12, 16\right)
-2
2
4
6
8
10
12
14
16
18
x
-2
2
4
6
8
10
12
14
16
18
y
b
A = \left(-4, -3\right), C = \left(3, -2\right)
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
3

What is the formula for the distance between two points A \left(x_{1}, y_{1}\right) and B \left(x_{2}, y_{2}\right) on the coordinate plane?

Let's practice
4

Consider \overline{AC} that has been graphed on the coordinate plane.

Find AC, rounding your answer to two decimal places.

a
-2
-1
1
2
3
4
x
1
2
3
4
5
6
7
8
9
y
b
-2
-1
1
2
3
4
5
6
7
8
9
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
5

Find the distance between Point A and Point B, rounding your answer to two decimal places if necessary.

a

A \left(1, 4\right) and B \left(7, 12\right)

b

A \left(4, 2\right) and B \left( - 8 , - 7 \right)

c

A \left( - 1 , 9\right) and B \left( - 4 , 1\right)

d

A \left(-1, - \dfrac{3}{5} \right) and B \left(4, \dfrac{12}{5}\right)

6

Given P \left(4, 3\right), M \left( - 3 , - 4 \right) and N \left( - 7 , 1\right):

a

Find the distance from P to M, rounding your answer to two decimal places.

b

Find the distance from P to N, rounding your answer to two decimal places.

c

Determine the point that is further from P.

7

A circle with center at point C \left(3, 4\right) has point A \left( - 12 , 12\right) lying on its circumference. Find the radius of the circle.

8

ABCD is a rhombus whose vertices are A \left(1, 2\right), B \left(3, 10\right), C \left(11, 12\right) and D \left(9, 4\right). Find the exact length of the diagonals:

a

\overline{AC}

b

\overline{BD}

Let's extend our thinking
9

Mateo is meeting his mom at the Meeting Spot shown on the map below after a doctor's appointment. They need to catch the train home.

a
Which of the three train stations is closest distance to their meeting spot?
b
What might not make the closest train station the best station to go to in reality?
c
If they needed to stop at the Winn-Dixie before going home, which station would have the shortest trip distance?
A map showing 6 streets, 3 stations, a hospital, a supermarket, and a marked point labeled Meeting Spot. Speak to your teacher for more information.
10

\overline{AM} is a vertical line segment which is 3 units long. If A is the point \left( - 2 , 6\right):

a
How many possible coordinates of M are there?
b
What are the possible coordinates of M?
c
How would your answers to parts (a) and (b) change if we were not told the line segment was vertical?
11

Explain the connections between the Pythagorean theorem and the distance formula.

12

Dayanna and David were asked for the formula for the distance between two points A \left(x_{1}, y_{1}\right) and B \left(x_{2}, y_{2}\right) on the coordinate plane.

Dayanna wrote AB = \sqrt{\left(x_{2} - x_{1}\right)^{2} + \left(y_{2} - y_{1}\right)^{2}}.

David wrote AB = \sqrt{\left(x_{1} - x_{2}\right)^{2} + \left(y_{1} - y_{2}\right)^{2}}.

Who is correct? Explain your answer.

13

Fyfe is asked to find the length of the line segment \overline{AB} with endpoints A \left(-4,7\right) and B \left(3,-5\right). Below is their solution.

1\displaystyle AB\displaystyle =\displaystyle \sqrt{\left(x_{2} - x_{1}\right)^{2} + \left(y_{2} - y_{1}\right)^{2}}Distance formula
2\displaystyle =\displaystyle \sqrt{\left(3 - \left(-5\right)\right)^{2} + \left(-4 - 7\right)^{2}}Substitution Property of Equality
3\displaystyle =\displaystyle \sqrt{\left(8\right)^{2} + \left(-11\right)^{2}}Simplify
4\displaystyle =\displaystyle \sqrt{64+121}Simplify
5\displaystyle =\displaystyle \sqrt{185}Simplify
a
Identify the step where Fyfe makes an error and explain their misunderstanding.
b
Correct Fyfe's work.
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Outcomes

G.N.Q.A.1

Use units as a way to understand real-world problems.*

G.N.Q.A.1.A

Use appropriate quantities in formulas, converting units as necessary.

G.GPE.A.3

Understand the relationship between the Pythagorean Theorem and the distance formula and use an efficient method to solve problems on the coordinate plane.

G.MP1

Make sense of problems and persevere in solving them.

G.MP2

Reason abstractly and quantitatively.

G.MP3

Construct viable arguments and critique the reasoning of others.

G.MP4

Model with mathematics.

G.MP5

Use appropriate tools strategically.

G.MP6

Attend to precision.

G.MP7

Look for and make use of structure.

G.MP8

Look for and express regularity in repeated reasoning.

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