This crazy week in Geometry - Similar Polygons.

This week in Geometry we are learning about applications of proportions using triangles and polygons. Here is an easy video discussing what we learned so far this week, concerning the mirror activity from Monday.

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In the video, the setup is little height over big height equaled to little shadow over big shadow.

In the video below, the teacher explains how to show that two polygons are similar. Here is another way, the corresponding parts are AE ~ QU and ED ~ UT. So when you divide AE by ED and divide QU by UT, you will get the same value. Check it out and see for yourself.

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Dilations in Chapter 7!

While talking about ratios, proportions and scale factors. We need to talk about dilations.
Here is a video on dilations.



Having watched the video, there are ways to prove that two shapes are dilations of each other:

• corresponding sides have the same slope
• corresponding sides have a common scale factor
• corresponding sides have distances that are multiples of each other
• the objects of an area that is a multiple of the scalar factor squared

Concentrate on finding the slopes of lines. That's the easiest to figure out above all other tests.


Apply the bullet points from above to the video below. Only pay attention to 0 minutes to 7:20 minutes. The rest we didn't cover and will not cover in class. Prove that the triangles are dilations. I will count is as extra credit if you turn this in by Friday, March 7, 2014.

Important Bellwork!

This bellwork is going to keep coming up in the next few weeks.

If the Earth takes 365.25 days to revolve around the Sun and is 1 astronomic unit from the Sun, how many astronomic units is Mars if it takes 686.9 days to revolve around the Sun? 

 

How many astronomic units is Saturn, if it takes 10832 days to revolve around the Sun?

Chapter 7

Today we are starting Chapter 7 - Similar Triangles and More. Below is the jargon for the chapter.

   

Day Two of Review for Chapter 5

Today in class, we continued are discussion about Chapter 5. On the test there will be questions about perpendicular bisectors (circumcenter), angle bisectors (incenter), altitudes (orthocenter), medians, midsegments, triangle inequalities, and vocabulary.

For the past two days, we had to answer questions like: (copy and paste the link through Google to see)

https://mail.google.com/mail/?ui=2&ik=6159f3bbcb&view=att&th=1444bedeb78671b7&attid=0.1&disp=safe&realattid=24febd0ca97e9b2f_0.1&zw

https://mail.google.com/mail/?ui=2&ik=6159f3bbcb&view=att&th=1444bee1a6dfe7d4&attid=0.1&disp=safe&realattid=821b0dd06ad9afb6_0.1&zw

Let's Continue the Chapter 5 Review

Today, let us review perpendicular bisectors, altitudes, angle bisectors, and medians. For the test you should know how to draw and label each one them.




Here is a video on a perpendicular bisector.


Here is a video on a the median of a triangle.


Here is a video on the altitude of a triangle.


Here is a video on the angle bisector of a triangle.

Chapter 5 Mid Review

So last week, we had 9 jargon words to summarize Chapter 5. They are altitude, median, perpendicular, bisector, inequality, comparison,circumcenter, incenter, and orthocenter.  Below are pictures from class of the work we did in making our graphic organizers.

Last week, we also practice making the orthocenter - intersection of 3 altitudes, the circumcenter - intersection of 3 perpendicular bisectors, and the incenter - interesection of 3 angle bisectors on a website called Geogebra.

Go to www.geogebra.org, through Google Chrome to practice.