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9.05 Classifying polygons in the coordinate plane

Adaptive
Worksheet
What do you remember?
1

State the properties of each of the following triangles that can be identified with coordinate geometry:

a
Scalene triangles
b
Isosceles triangles
c
Equilateral triangles
d
Right triangles
2

Consider the quadrilateral formed by the points A \left( - 3 , - 4 \right), B \left(5, - 4 \right), C \left(5, 4\right) and D \left( - 3 , 4\right).

a

Find the length of the following sides:

i

\overline{AB}

ii

\overline{BC}

iii

\overline{CD}

iv

\overline{DA}

b

State if all sides of the quadrilateral congruent.

c

State if all consecutive sides are perpendicular.

d

Now, classify the quadrilateral as precisely as possible.

-5
-4
-3
-2
-1
1
2
3
4
5
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
3

Consider the triangle shown.

a

Find the slope of the following sides:

i

\overline{AC}

ii

\overline{BC}

b

Calculate the side lengths of all three sides.

c

Classify the triangle as precisely as possible.

-10
-8
-6
-4
-2
2
x
-6
-4
-2
2
4
6
y
4

Consider the quadrilateral ABCD.

a

Find the slope of the following sides:

i
\overline{AB}
ii
\overline{CD}
iii

\overline{AD}

iv

\overline{BC}

b

Classify this quadrilateral as precisely as possible.

-8
-6
-4
-2
2
4
6
8
x
-2
-1
1
2
3
4
5
6
y
Let's practice
5

Isolda is designing a house using a graphing software. The outer pieces of the triangular roof trusses must form an isosceles triangle. The outer pieces of one of the triangular trusses is formed by three points: A \left(2,2 \right), B\left(-2, 0\right) and C \left(6, 0\right).

a

Calculate the following lengths:

i

BC

ii

AB

iii

AC

b

State if this is a possible roof truss.

A diagram of the trusses of a roof. A triangle labeled A B C is drawn to show the outline of the roof truss.
6

Consider the quadrilateral ABCD.

Classify this quadrilateral as precisely as possible.

-3
-2
-1
1
2
3
4
5
6
x
-3
-2
-1
1
2
3
4
5
6
y
7

Consider a quadrilateral with vertices A \left(3, 4\right), B \left(6, 2\right), C \left(5, - 3 \right), and D \left( - 4 , 3\right).

a

Plot the quadrilateral on a coordinate plane.

b

Classify the quadrilateral ABCD as precisely as possible.

8

Consider a quadrilateral with vertices P \left(4, - 4\right), Q \left(5, - 7\right), R \left(1, - 11\right) and S \left(0,- 8\right).

Classify the quadrilateral PQRS as precisely as possible.

9

A triangle consists of the points A \left(-2,-2\right), B \left(1, -4\right) and C \left(5,2\right).

Classify \triangle ABC as precisely as possible.

10

Consider the following lines:

  • Line P: y = - 6 x - 4

  • Line Q: y = \dfrac{x}{6} + 6

  • Line R: y = - 6 x - 1

  • Line S: y = \dfrac{x}{6} + 1

a

Find the slope of each line:

i

m_{P}

ii

m_{Q}

iii

m_{R}

iv

m_{S}

b

State the type of the quadrilateral enclosed by the four lines.

11

Quadrilateral ABCD has vertices A \left(1,- 2\right), B \left(9,3\right), C \left(7,- 1\right) and D \left(- 1, - 6\right).

Show that the diagonals bisect each other and therefore that ABCD is a parallelogram.

Let's extend our thinking
12

Quadrilateral RSTU has vertices R \left(3, 0\right), S \left(5, - 3 \right), T \left(-1, - 7 \right), U \left( - 3 , - 4 \right).

Classify the quadrilateral RSTU as precisely as possible. Justify your answer.

13

Show that the given quadrilateral is a trapezoid, but not an isosceles trapezoid.

-4
-3
-2
-1
1
2
3
4
5
x
-3
-2
-1
1
2
3
4
5
6
7
y
14

Consider the points P \left( - 20 , - 18 \right), Q \left(-6, -1\right) and R \left( 4 , 2\right).

Determine the coordinates of a point S such that PQRS is a parallelogram. Justify your answer.

-20
-16
-12
-8
-4
4
8
x
-20
-16
-12
-8
-4
4
8
y
15

Describe two ways in which you can show whether or not a quadrilateral in the coordinate plane is a square. Explain which method is more efficient.

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Outcomes

G.GPE.A.1

Use coordinates to justify geometric relationships algebraically and to solve problems.

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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