2.02 Make Scale Drawings with Ratio Method - Activity

Creating a scale drawing using the ratio method:

[list=1][*]Draw a ray [icon]/images/ggb/toolbar/mode_ray.png[/icon] beginning at the center through each vertex of the figure.[/*][*]Dilate each vertex along the appropriate ray by the scale factor. For example for a scale factor r = 1/2, find the midpoint [icon]/images/ggb/toolbar/mode_mirroratpoint.png[/icon] between the center and each vertex.[/*][*]Use the polygon tool [icon]/images/ggb/toolbar/mode_polygon.png[/icon] to join the vertices in the way they are joined in the original figure.[br][/*][/list]

Create a scale drawing of triangle ABC about center D and scale factor r = 1/2.

How can we verify whether your triangle really is a scale drawing of triangle ABC?

Finding the location of center:

[list=1][*]Draw a ray beginning at A through A'. Repeat for each corresponding vertex of the figure.[/*][*]Mark the point of intersection of the rays. This point is the center.[br][/*][/list]

Find the location of the center.

One of the following images shows a well-scaled drawing of triangle ABC done by the ratio method; the other image is not a well-scaled drawing. [br][br]Use your tools to make the necessary measurements and show the calculations that determine which is a scale drawing and which is not.

Figure 1

Figure 2

Which image is a scale drawing?

Figure 1 Figure 2

Explain your answer above.