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Common Core For Geometry

Worksheets for Geometry, Module 2, Lesson 17

Student Outcomes

- Students prove the side-angle-side criterion for two triangles to be similar and use it to solve triangle problems.
- Students prove the side-side-side criterion for two triangles to be similar and use it to solve triangle problems.

**The Side-Angle-Side (SAS) and Side-Side-Side (SSS) Criteria for Two Triangles to Be Similar**

Classwork

**Opening Exercise**

a. Choose three lengths that represent the sides of a triangle. Draw the triangle with your chosen lengths using
construction tools.

b. Multiply each length in your original triangle by 2 to get three corresponding lengths of sides for a second
triangle. Draw your second triangle using construction tools.

c. Do your constructed triangles appear to be similar? Explain your answer.

d. Do you think that the triangles can be shown to be similar without knowing the angle measures?

**Exploratory Challenge 1/Exercises 1β2**

- Examine the figure, and answer the questions to determine whether or not the triangles shown are similar.

a. What information is given about the triangles in Figure 1?

b. How can the information provided be used to determine whether β³ π΄π΅πΆ is similar to β³ π΄π΅β²πΆβ²?

c. Compare the corresponding side lengths of β³ π΄π΅πΆ and β³ π΄π΅β²πΆβ². What do you notice?

d. Based on your work in parts (a)β(c), draw a conclusion about the relationship between β³ π΄π΅πΆ and β³ π΄π΅β²πΆβ².

Explain your reasoning. - Examine the figure, and answer the questions to determine whether or not the triangles shown are similar.

a. What information is given about the triangles in Figure 2?

b. How can the information provided be used to determine whether β³ πππ is similar to β³ ππβ²π β²?

c. Compare the corresponding side lengths of β³ πππ and β³ ππβ²π β². What do you notice?

d. Based on your work in parts (a)β(c), draw a conclusion about the relationship between β³ πππ and β³ ππβ²π β². Explain your reasoning.

**Exploratory Challenge 2/Exercises 3β4**

- Examine the figure, and answer the questions to determine whether or not the triangles shown are similar.

a. What information is given about the triangles in Figure 3?

b. How can the information provided be used to determine whether β³ π΄π΅πΆ is similar to β³ π΄π΅β²πΆβ²?

c. Compare the corresponding side lengths of β³ π΄π΅πΆ and β³ π΄π΅β²πΆβ². What do you notice?

d. Based on your work in parts (a)β(c), make a conjecture about the relationship between β³ π΄π΅πΆ and β³ π΄π΅β²πΆβ².

Explain your reasoning. - Examine the figure, and answer the questions to determine whether or not the triangles shown are similar.

a. What information is given about the triangles in Figure 4?

b. How can the information provided be used to determine whether β³ π΄π΅πΆ is similar to β³ π΄π΅β²πΆβ²?

c. Compare the corresponding side lengths of β³ π΄π΅πΆ and β³ π΄π΅β²πΆβ². What do you notice?

d. Based on your work in parts (a)β(c), make a conjecture about the relationship between β³ π΄π΅πΆ and β³ π΄π΅β²πΆβ². Explain your reasoning.

**Exercises 5β10**

- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.9. Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.
- Are the triangles shown below similar? Explain. If the triangles are similar, write the similarity statement.

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