GeoGebra Classroom

# Dilation and similar triangles

Instruction: In the applet below, AB'C' is a dilation image of ABC with Point A as the dilation center. You may interact with the applet by drag B' to change the image of dilation (light blue image); drag C or B to change the shape of triangles and move the location of the side BC. Interact with the applet for a few minutes, then try to answer the questions below.

## Q2: Based on your observation, what is the relationship between line BC and B'C'? How do you prove it?

Below is the demonstration of the dilation of line segment BC with O as the dilation center. You can change the scale factor by sliding the grey bar, you can move the location of O, B, C by drag the point around, and you can change the location of BC by dragging the segment BC. Interact with the applet for a few minutes, then try to answer the questions below.

Q3: What do you think comparing this activity with the one we just did above?

Q4: What conclusion or conjecture can you draw from this applet about the dilation of a line segment?

Q5: What will happen if BC is a line instead of a line segment?