IM 7.1.2 Lesson: Corresponding Parts and Scale Factors

Find each product mentally.

[math]\frac{1}{4}\cdot32[/math]

[math]7.2\cdot\frac{1}{9}[/math]

[math]\frac{1}{4}\cdot5.6[/math]

A road sign for railroad crossings is a circle with a large X in the middle and two R’s. Here is a picture with some points labeled and two copies of the picture. Use the angle tool to compare the angles in the copies and in the original.

Complete this table to show corresponding parts in the three pictures.

Is either copy a scaled copy of the original road sign? Explain your reasoning.[br]

Use the moveable angle tool to compare angle KLM with its corresponding angles in Copy 1 and Copy 2.

What do you notice?

Use the moveable angle tool to compare angle NOP with its corresponding angles in Copy 1 and Copy 2.

What do you notice?

Here is Triangle O, followed by a number of other triangles.

[br]Which of the triangles is a scaled copy of Triangle O?

A B C E D G F H

Explain your reasoning for choosing each triangle.

List all the triangles that are scaled copies in the table. Record the side lengths that correspond to the side lengths of Triangle O listed in each column.

Explain or show how each scaled copy triangle has been scaled from the original (Triangle O).

Choose one of the triangles that is not a scaled copy of Triangle O. Describe how you could change at least one side to make a scaled copy, while leaving at least one side unchanged.