Download CCGPS 11 Proving Two Triangles are Congruent

Georgia Department of Education
Common Core Georgia Performance Standards Framework Student Edition
Analytic Geometry Unit 1
Proving Two Triangles are Congruent
Mathematical goals
Knowing that rigid transformations preserve size and shape or distance and angle, use this
fact to connect the idea of congruency and develop the definition of congruent.
Use the definition of congruence, based on rigid motion, to show two triangles are congruent
if and only if their corresponding sides and corresponding angles are congruent.
Use the definition of congruence, based on rigid motion, to develop and explain the triangle
congruence criteria; ASA, SSS, and SAS, AAS.
Common Core State Standards
MCC9-12.G.CO.6 Use geometric descriptions of rigid motions to transform figures and to
predict the effect of a given rigid motion on a given figure; given two figures, use the definition
of congruence in terms of rigid motions to decide if they are congruent.
MCC9-12.G.CO.7 Use the definition of congruence in terms of rigid motions to show that two
triangles are congruent if and only if corresponding pairs of sides and corresponding pairs of
angles are congruent.
MCC9-12.G.CO.8 Explain how the criteria for triangle congruence (ASA, SAS, and SSS)
follow from the definition of congruence in terms of rigid motions.
Standards for Mathematical Practice
4. Model with mathematics.
5. Use appropriate tools strategically.
6. Attend to precision.
7. Look for and make use of structure.
8. Look for and express regularity in repeated reasoning.
Triangle Investigations: Station 1
1. Draw a triangle of any size and shape and label it ABC.
2. Using the ruler and protractor, measure and record the angles and sides of the triangle.
Remember the total degrees in any triangle should be _______?
3. Draw DOG where AB=DO, BC=OG, and AC=DG.
4. Measure and record the angles of DOG, how are they related to the angles of ABC?
5. What can you say about ABC and DOG?
MATHEMATICS ANALYTIC GEOMETRY UNIT 1: Similarity, Congruence, and Proofs
Georgia Department of Education
Dr. John D. Barge, State School Superintendent
May, 2012 Page 52 of 73
All Rights Reserved
Georgia Department of Education
Common Core Georgia Performance Standards Framework Student Edition
Analytic Geometry Unit 1
Triangle Investigations: Station 2
1. Draw KIT where KI=5 cm.
2. Using a protractor and point K as a vertex draw a 60o angle with side length 11cm (label
point T).
3. Connect point T to point I.
4. Measure the sides and angles of KIT.
5. Now draw a line segment of 11cm. Name it FG.
6. Using point F as your vertex draw a 60o angle with side length 5 cm. label point H.
7. Connect point G to point H.
8. Measure the sides and angles of FGH.
9. Are triangles KIT and FGH congruent?
Triangle Investigations: Station 3
1.
2.
3.
4.
Draw a line segment that is 7cm long. Label it ML.
Using point L as a vertex draw a 38o angle.
Draw a line segment beginning at point M that is 5 cm long and hits the side of the angle?
Repeat steps 1-2. This time connect the 5 cm segment at a different point on the side of
the angle.
5. Are the 2 triangles congruent?
Triangle Investigations: Station 4
1.
2.
3.
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5.
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7.
8.
9.
Draw a line segment LM that is 7 inches long.
Using point L as a vertex draw a 35oangle.
Using point M as a vertex draw a 57o angle.
Label the point of intersection of the two angles as N. This is triangle LMN.
Draw line segment ST that is 7 inches long.
Using point S as a vertex draw a 35 o angle.
Using point T as a vertex draw a 57o angle.
Label the point of intersection of the two angles as U. This is triangle STU
Hold up the two triangles - are they congruent?
MATHEMATICS ANALYTIC GEOMETRY UNIT 1: Similarity, Congruence, and Proofs
Georgia Department of Education
Dr. John D. Barge, State School Superintendent
May, 2012 Page 53 of 73
All Rights Reserved
Georgia Department of Education
Common Core Georgia Performance Standards Framework Student Edition
Analytic Geometry Unit 1
Triangle Investigations: Station 5
Practice with Triangle Congruence
State whether each pair of triangles is congruent by SSS, SAS, ASA, AAS, or HL; if none of
these methods work, write N. If congruent, make a congruence statement for the triangles.
U
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B
MATHEMATICS ANALYTIC GEOMETRY UNIT 1: Similarity, Congruence, and Proofs
Georgia Department of Education
Dr. John D. Barge, State School Superintendent
May, 2012 Page 54 of 73
All Rights Reserved
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