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9.06 Circles in the coordinate plane

Adaptive
Worksheet
What do you remember?
1

State the equation for a circle with center \left(h,k\right) and radius r.

2

Consider the graph of the circle shown.

Copy and complete the following statement:

Every point on the circle is exactly ⬚ units away from the point (⬚ ,⬚).

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

For each of the following circle graphs:

i
State the coordinates of the center.
ii
State the radius of the circle.
iii
State the diameter of the circle.
iv
State the equation of the circle.
a
-5
-4
-3
-2
-1
1
2
3
4
5
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
b
-3
-2
-1
1
2
3
4
5
x
-6
-5
-4
-3
-2
-1
1
2
y
4

Consider the circle with the equation (x-2)^2+(y+3)^2=75.

a

State the center of the circle.

b

Calculate the radius of the circle.

c

Calculate the diameter of the circle.

d

Calculate the circumference of the circle.

Let's practice
5

For each of the following descriptions, write the equation of the circle.

a

A circle with center at (3, 3) and a radius of 6 units.

b

A circle with center at \left(0, 6\right) and a diameter of 6 units.

c

A circle with center at \left(\dfrac{17}{2},0\right) and a diameter of 2\sqrt{15} units.

6

For each of the following equations:

i

Find the center of the circle.

ii

Find the radius of the circle.

iii

Graph the circle.

iv
State the domain and range.
a
x^{2} + y^{2} = 16
b
\left(x + 4\right)^{2} + \left(y - 2\right)^{2} = 25
7

Using the given center and another point for the following circles:

i

Find the radius of the circle.

ii

Find the equation of the circle.

a
Center at \left(-2,5\right), passing through the point \left(3,-7\right)
b
Center at \left(0,0\right), passing through the point \left(5,-10\right)
8

Determine whether the following points are inside, outside, or on the circle with equation x^{2} + y^{2} = 25.

a
(- 3, 2)
b
(4, 3)
c
(1, 6)
d
(-5,0)
9

For each of the following equations of a circle:

i

Rewrite the equation of the circle in standard form by completing the square.

ii

Sketch the graph of this circle.

a

x^{2} - 12 x +y^{2} + 2 y + 1 = 0

b

4x^2 + 4y^2 +12x - 36y + 41=0

10

For each of the following circles:

i

Find the radius of the circle.

ii

Find the circumference of the circle.

iii

Find the area of the circle.

a

\left(x-3\right)^2+\left(y+4\right)^2=25

b

\left(x+2\right)^2+\left(y-1\right)^2=9

c

\left(x+6\right)^2+\left(y-2\right)^2=81

d

\left(x-1\right)^2+\left(y+9\right)^2=12

e

Center at \left(-3,5\right) passing through the point \left(1,2\right)

f

Center at \left(6,2\right) passing through the point \left(-3,-1\right)

g

x^2+y^2+6y-16=0

h

x^2-10x+y^2+8y+40=0

11

A wind turbine has 20\text{ m} long blades that are attached to a tower 30\text{ m} high. The distance from the origin to the base of the wind turbine is 25\text{ m}.

Find the standard form of the equation of the circle represented by the path of the blades of the wind turbine.

A figure of a wind turbine imposed on a first quadrant coordinate plane without numbers. The wind turbine has 3 identical blades with a length of 20 meters. The horizontal distance between the origin and the center of the turbine's base is 25 meters. The vertical distance between the rotor and the x axis is 30 meters.
Let's extend our thinking
12

A soccer match is being televised.

One of the cameras is mounted on a drone which is programmed to zoom in on the ball only when it is inside the center circle.

The drone uses a coordinate system to track the position of the ball, where the origin is at the bottom left corner of the field and each unit corresponds to 1\text{ m}.

A diagram of a soccer field that has a length of 99 meters, and width of 75 meters. The center circle of the soccer field has a radius of 9.15 meters.
a

The center of the center circle is in the exact center of the field. Find the coordinates of the circle's center.

b

Find the radius of the center circle.

c

State the equation for the circle.

d

State the domain and range of the circle in interval notation.

13

Coralee needs to use her school’s laser cutter to make a cork component for her design project.

Using technology to sketch the component, she knows that the intersection of two different sized circles inscribed on a piece of cork gives the shape that she wants.

Two overlapping circles in a rectangle. A dashed line connects the centers of the circles. The region where the two circles overlapped is shaded.

Two such circles have the equations \left(x - 12\right)^{2} + \left(y - 8\right)^{2} = 49 and

\left(x - 20\right)^{2} + \left(y - 8\right)^{2}= 36, where each unit is 1\text{ cm} and \left(0, 0\right) is the bottom left corner of the given cork board.

a

State the domain and range of the leftmost circle in interval notation.

b

State the domain and range of the rightmost circle in interval notation.

c

Find the width of the component that Coralee wants to make.

d

Find the least area of material that could be used to make Coralee's shape, considering the following constraints:

  • The laser cutter will only accept rectangular pieces of material.

  • The height of the intersection is 10.17\text{ cm}.

  • There also needs to be a gap of at least 1\text{ cm} between any cut and the edge of the piece.

14

A circle has a diameter with endpoints of A\left(-1,1\right) and B\left(9,-7\right).

a

Determine the equation of the circle.

b

Show that the point P\left(8,3\right) is outside of the circle.

15

Three receiving stations are located on a coordinate plane, where each unit is one mile, at the points \left( - 3 , - 2 \right), \left( - 1 , 2\right) and \left(3, 1\right). The epicenter of an earthquake is determined to be 2 miles, 4 miles and 5 miles from these three points, respectively.

a

Determine the coordinates of the epicenter of the earthquake.

b

The earthquake can be felt 10 miles away. Determine if the town located at \left(8,-7\right) would feel the earthquake.

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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.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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