Corresponding Parts and Scale Factors

Investigating Corresponding Parts and Scale Factor.

A road sign for railroad crossings is a circle with a large X in the middle and two R’s. Here below is a picture with some points labeled and two copies of the picture.

  • Drag the elements in the rectangular boxes and place them as corresponding parts in the three pictures.​

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

(2). What do you notice?

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

(4). What do you notice?

Identify Scaled Copies of a Triangle.

In the figure below is Triangle O, followed by a number of other triangles.

(1). Which of the triangles is a scaled copy of Triangle O? Explain your reasoning for choosing each triangle.

(2). 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.

(1). These triangles are scaled copies of each other. What is the scale factor?

(2). These rectangles are scaled copies of each other. What is the scale factor?

(3). These rectangles are scaled copies of each other. What is the scale factor from ABCD to UVWX?