Similarity in Triangles

Open Ended

For Triangle A and Triangle B, some of the angle measures are given in degrees: Triangle A: 53, 71, $$\underline{\hspace{.5in}}$$ ; Triangle B: 53, 71, $$\underline{\hspace{.5in}}$$ . Use the information to decide if the triangles are similar or not. Explain how you know.

Open Ended

For Triangle C and Triangle D, some of the angle measures are given in degrees: Triangle C: 90, 37, $$\underline{\hspace{.5in}}$$ ; Triangle D: 90, 53, $$\underline{\hspace{.5in}}$$ . Use the information to decide if the triangles are similar or not. Explain how you know.

Open Ended

For Triangle E and Triangle F, some of the angle measures are given in degrees: Triangle E: 63, 45, $$\underline{\hspace{.5in}}$$ ; Triangle F: 14, 71, $$\underline{\hspace{.5in}}$$ . Use the information to decide if the triangles are similar or not. Explain how you know.

Open Ended

For Triangle G and Triangle H, some of the angle measures are given in degrees: Triangle G: 121, $$\underline{\hspace{.5in}}$$ , $$\underline{\hspace{.5in}}$$ ; Triangle H: 70, $$\underline{\hspace{.5in}}$$ , $$\underline{\hspace{.5in}}$$ . Use the information to decide if the triangles are similar or not. Explain how you know.

Draw

Draw 2 equilateral triangles that are not congruent.

Multiple Choice

Measure the side lengths and angles of your triangles. Are the 2 triangles similar?

• Yes, the triangles are similar.
• The triangles have different angles but are similar.

Open Ended

Do you think 2 equilateral triangles will be similar always, sometimes, or never? Explain your reasoning.

Open Ended

In the figure, line segment $$BC$$ is parallel to line segment $$DE$$ . Explain why triangle $$ABC$$ is similar to triangle $$ADE$$ .

Open Ended

Explain why triangle ABC is similar to EDC.

Multiple Choice

What are the missing side lengths in the triangles shown in the image?

• BC = 22, DE = 10
• BC = 18, DE = 25
• BC = 30, DE = 20
• BC = 24, DE = 15