Construct Tangent Lines from Outside a Circle: CCSS.Math.Content.HSG-C.A.4 - Common Core: High School - Geometry

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Question

C.a.4 1

Construct a line that is tangent to a point on the circle and passes through the point .

Answer

To construct a line that is tangent to a point on the circle and passes through the point , recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Using the plotted circle and the given point, two potential lines can be drawn that will touch the circle at one point. One possible line would touch the circle on the top half of the circumference while the other potential line would touch the circle on the bottom.

C.a.4 1

Constructing the first potential tangent line, a point can be plotted on the circle as follows.

C.a.4 2

From here, connect the given point to the point on the circle with a straight line. Thus resulting in a tangent line to the circle.

C.a.4 3

Of the other answer choices, two options contain lines that are secant to the circle meaning that the line intersects the circle at point two points thus, those options are not tangent. The other two lines do not intersect nor touch the circle therefore they are not considered tangent either.

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Question

C.a.4 1
Construct a line that is tangent to a point on the circle and passes through the point .

Answer

To construct a line that is tangent to a point on the circle and passes through the point , recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Using the plotted circle and the given point, two potential lines can be drawn that will touch the circle at one point. One possible line would touch the circle on the top half of the circumference while the other potential line would touch the circle on the bottom.

C.a.4 1

Constructing the second potential tangent line, a point can be plotted on the circle as follows.

From here, connect the given point to the point on the circle with a straight line. Thus resulting in a tangent line to the circle.

C.a.4 1 bottom line

Of the other answer choices, two options contain lines that are secant to the circle meaning that the line intersects the circle at point two points thus, those options are not tangent. The other two lines do not intersect nor touch the circle therefore they are not considered tangent either.

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Question

Calculate a point that is tangent to the circle and passes through the origin.

Answer

To construct a line that is tangent to a point on the circle and passes through the origin, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Given the equation of the circle,

the center and radius of the circle can be determined.

The center is located at and the radius is .

Therefore, the center is located at and the radius is three. Plotting the circle and tangent line to the origin results in the following.

Screen shot 2016 07 14 at 10.07.14 am

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Question

Calculate a point that is tangent to the circle and passes through the origin.

Answer

explain

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Question

Calculate a point that is tangent to the circle and passes through the point .

Answer

To construct a line that is tangent to a point on the circle and passes through the point , recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Given the equation of the circle,

the center and radius of the circle can be determined.

The center is located at and the radius is .

Therefore, the center is located at and the radius is three. Plotting the circle and tangent line to the point results in the following.

Screen shot 2016 07 14 at 10.42.33 am

Therefore, the point on the circle that creates a tangent line, .

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Question

Calculate a point that is tangent to the circle and passes through the point .

Answer

To construct a line that is tangent to a point on the circle and passes through the point , recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Given the equation of the circle,

the center and radius of the circle can be determined.

The center is located at and the radius is .

Therefore, the center is located at and the radius is three. Plotting the circle and tangent line to the point results in the following.

Screen shot 2016 07 14 at 10.53.27 am

Therefore, the point on the circle that creates a tangent line with the point given is .

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Question

Plot1

Construct a line that is tangent to a point on the circle and passes through the point plotted outside the circle.

Answer

To construct a line that is tangent to a point on the circle and passes through the point outside the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Using the plotted circle and the given point, two potential lines can be drawn that will touch the circle at one point. One possible line would touch the circle on the left half of the circumference while the other potential line would touch the circle on the right half.

Plot1

Constructing a potential tangent line, a point can be plotted on the circle as follows.

From here, connect the given point outside the circle to the point on the circle with a straight line. Thus resulting in a tangent line to the circle.

Plot2.1

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Question

Determine whether the statement is true or false.

Plot12.1

The line is tangent to the circle.

Answer

To construct a line that is tangent to a point on the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Looking at the image, it is seen that the line only touches the circle once therefore, the line is tangent to the circle. Thus this statement is true.

Plot12.1

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Question

Plot4

Construct a line that is tangent to the circle.

Answer

To construct a line that is tangent to a point on the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Using the plotted circle one possible line would touch the circle is as follows.

Plot4.1

Thus resulting in a tangent line to the circle.

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Question

Plot10

Construct a line that is tangent to a point on the circle and passes through the point plotted outside the circle.

Answer

To construct a line that is tangent to a point on the circle and passes through the point outside the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Using the plotted circle and the given point, two potential lines can be drawn that will touch the circle at one point. One possible line would touch the circle on the left half of the circumference while the other potential line would touch the circle on the right half.

Plot10

Constructing a potential tangent line, a point can be plotted on the circle as follows.

From here, connect the given point outside the circle to the point on the circle with a straight line. Thus resulting in a tangent line to the circle.

Plot10.1

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Question

Determine whether the statement is true or false.

Given a circle, a tangent line to the circle can be constructed if it intersects the circle at two points.

Answer

To construct a line that is tangent to a point on the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Therefore, by definition the statement is false.

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Question

Determine whether the statement is true or false.

Plot1

A tangent line to the circle can be constructed between the point at and a point on the circle.

Answer

To construct a line that is tangent to a point on the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Plot1

Constructing the tangent line results in the following image,

Plot2.1

Therefore, this statement is true.

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Question

Determine whether the statement is true or false.

Plot9.1

The line is tangent to the circle.

Answer

To construct a line that is tangent to a point on the circle, recall what it means for a line to be "tangent". A line that is tangent to a point on a circle means that the line will only touch the circle at that specific point.

Therefore, looking at the graph

Plot9.1

it is seen that the line only intersects the circle once. Thus, the statement "The line is tangent to the circle." is true.

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