IM Geometry Unit 3 Lesson 5

Here’s a triangle ABC withmidpoints L, M, and N.

What do you notice? What do you wonder?

Here’s a triangle ABC. Points M and N are the midpoints of 2 sides.

Convince yourself triangle ABC is a dilation of triangle AMN. What is the center of the dilation? What is the scale factor?

Prove that BC = 2MN.

Here is

. M is

of the way from A to B. N is

of the way from A to C.

What can you say about segment MN, compared to segment BC? Provide a reason for each of your conjectures.

IM G Unit 3 Lesson 5 from IM Geometry by Illustrative Mathematics, https://im.kendallhunt.com/HS/students/2/3/5/index.html. Licensed under the Creative Commons Attribution 4.0 license, https://creativecommons.org/licenses/by/4.0/.

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