Common Core: High School - Geometry : Congruence

Study concepts, example questions & explanations for Common Core: High School - Geometry

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All Common Core: High School - Geometry Resources

6 Diagnostic Tests 114 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #3 : Prove Theorems About Triangles.

Fill in the blanks below to complete the proof for the HL Theorem.  Use the figure below to find the given information.

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Possible Answers:

altitude, perpendicular, 

angle bisector, bisector, 

perpendicular, altitude, 

Correct answer:

altitude, perpendicular, 

Explanation:

 Follow the detailed proof below.

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Example Question #4 : Prove Theorems About Triangles.

The triangle inequality theorem states that if you have a triangle  then 

Fill in the blanks for the proof of the theorem below using triangle 

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To begin this proof we first must let there exist the triangle , where the length of  and  is a shared side between the two triangles.

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Possible Answers:

equilateral triangle, 

isosceles triangle, 

obtuse triangle, 

Correct answer:

isosceles triangle, 

Explanation:

Follow the detailed proof below for an explanation.

To begin this proof we first must let there exist the triangle , where the length of  and  is a shared side between the two triangles.

Screen shot 2020 08 12 at 9.55.00 am

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Example Question #5 : Prove Theorems About Triangles.

Fill in the blanks to the proof below.  We are proving that the base angles of isosceles triangles,  , are congruent.  This is a proof of the isosceles triangle theorem.

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Possible Answers:

, congruent, angle bisector, SAS

, similar, angle bisector, SAS

, congruent, midpoint, ASA

Correct answer:

, congruent, angle bisector, SAS

Explanation:

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Example Question #6 : Prove Theorems About Triangles.

Prove that if one side of a triangle is longer than another side of the same triangle, then the angle opposite the longer side will be greater than the angle opposite the shorter side.  Use the information that  for triangle .

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Possible Answers:

Proof:

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Proof:

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Proof:

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Correct answer:

Proof:

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Explanation:

Follow the detailed proof below.

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Example Question #1 : Draw Generalized Transformed Figures

If a triangle is in quadrant three and undergoes a transformation that moves each of its coordinate points to the left three units and down one unit, what transformation has occurred?

Possible Answers:

Extension

Reflection

Translation

None of the other answers.

Rotation

Correct answer:

Translation

Explanation:

To determine the type of transformation that is occurring in this particular situation, first recall the different types of transformations.

Translation: To move an object from its original position a certain distance without changing the object in any other way.

Transformation: Refers to any of the four changes that can be done to an object geographically. Transformations include, reflections, translations, rotations, and resizing the object.

Reflection: To flip the orientation of an object over a specific line or function.

Rotation: To rotate an object either clockwise or counter clockwise around a center point.

Since each of the triangle's coordinates is moved to the left and down, it is seen that the size and shape of the triangle remains the same but its location is different. Therefore, the transformation the triangle has undergone is a translation.

Example Question #191 : Congruence

If a rectangle has the coordinate values, , , , and  and after a transformation results in the coordinates , , , and  identify the transformation.

Possible Answers:

Dilation

None of the other answers.

Extension

Rotation

Reflection

Correct answer:

Reflection

Explanation:

"If a rectangle has the coordinate values, , and  and after a transformation results in the coordinates , and  identify the transformation."

A transformation that changes the  values by multiplying them by negative one is known as a reflection across the -axis or the line  

Therefore, this particular rectangle is being reflected across the -axis because the opposite of all the  values have been taken.

Example Question #2 : Draw Generalized Transformed Figures

If a rectangle has the coordinate values, , and  and after a transformation results in the coordinates , and  identify the transformation.

Possible Answers:

None of the other answers.

Dilation

Reflection

Translation

Rotation

Correct answer:

Translation

Explanation:

To identify the transformation that is occurring in this particular problem, recall the different transformations.

Translation: To move an object from its original position a certain distance without changing the object in any other way.

Transformation: Refers to any of the four changes that can be done to an object geographically. Transformations include, reflections, translations, rotations, and resizing the object.

Reflection: To flip the orientation of an object over a specific line or function.

Rotation: To rotate an object either clockwise or counter clockwise around a center point.

Looking at the starting and ending coordinates of the rectangle,

 , and   to  , and 

Since all the  coordinates are increasing by two this is known as a translation.

Example Question #3 : Draw Generalized Transformed Figures

If a rectangle has the coordinate values, , and  and after a transformation results in the coordinates , and  identify the transformation.

Possible Answers:

Extension

Reflection

Dilation

None of the others

Rotations

Correct answer:

Reflection

Explanation:

"If a rectangle has the coordinate values, , and  and after a transformation results in the coordinates  , and  identify the transformation."

A transformation that changes the  values by multiplying them by negative one is known as a reflection across the -axis or the line  

Therefore, this particular rectangle is being reflected across the -axis because the opposite of all the  values have been taken.

Example Question #5 : Draw Generalized Transformed Figures

Assume the values a, b, c, and d are all positive integers. If a rectangle has the coordinate values, (a,b)(c,b)(a,d), and (c,d) and after a transformation results in the coordinates (a,b)(2c,b)(a,2d), and (2c,2d) identify the transformation.

Possible Answers:

None of the above

Reflection

Dilation

Rotation

Transformation

Correct answer:

Dilation

Explanation:

The above described transformation is a dilation. Notice that one point, (a,b), stays the same before and after the transformation. The point (c,b) retains the same y value of b, but c is dilated into 2c, extending the base of the rectangle. The point (a,d) is similar in that the x value of a stays the same, but the y value of d is extended or dilated to 2d. The final point (c,d) is extended in both length and width to become (2c,2d). The below graph shows the original figure in blue and the dilated larger figure in pink. 

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Example Question #1 : Draw Generalized Transformed Figures

Imagine a triangle with vertices located at the points (a,b), (c,d), and (e,f). If this figure were rotated 180o about the origin, what would be the new coordinates of the triangle's vertices?

Possible Answers:

(-a,b), (-c,d), and (-e,f)

(a,-b), (c,-d), and (e,-f)

(-a,-b), (-c,-d), and (-e,-f)

(a,b), (-c,-d), and (-e,-f)

(a,b), (c,d), and (e,f)

Correct answer:

(-a,-b), (-c,-d), and (-e,-f)

Explanation:

The correct answer is (-a,-b), (-c,-d), and (-e,-f). In other words, you'd just take the opposite value of each x and y value of each vertex of the triangle. The following diagram shows one set of vertexes rotated 180o about the origin to help demonstrate this. 

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Please note that if one of our original points had any negative values, such as the point (2,-2), and we rotated it 180o about the origin, the signs of both the x and y values would change, and this point's image after translation would be (-2,2). 

All Common Core: High School - Geometry Resources

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