1. Before the Bell… Open to a blank page in your notes… Get out a pencil…not a pen

2. On a piece of paper in your notes… Copy down this diagram and TRY TO find the circumference of the circle, using the given information. A B 9 degrees The distance from A to B is 10 meters.

3. Eratosthenes Method to Finding Circumference of Earth Answer these questions to get you started understanding… – State the alternate interior angle hypothesis in your own words… – Why is it strange its considered a hypothesis? – Where does the sun shine its rays at 90 degrees on the summer solstice? – If you were standing somewhere at noon in that area (question above) on the summer solstice…what would your shadow look like? Why? – If someone was standing on a different location on Earth during the summer solstice, what would their shadow look like compared to someone of tropic of Cancer? – Where does the sun shine its rays at 90 degrees on the autumnal equinox?

4. How does the sun cast different shadows in different locations? Eratosthenes YouTube Video This is my Homeboy Carl Sagan-  Eratosthenes YouTube Video 2

6. Eratosthenes YouTube Video This is my Homeboy Carl Sagan-  Eratosthenes YouTube Video 2 This is my Homeboy Carl Sagan-  Eratosthenes YouTube Video 2

7. Let’s see if you understand… What was unique about the town of Syene’s location…and what happened there that was “special”. What does getting the shadow angle help us find about our specific location? Why does this help us find the circumference of earth?

8. So How Do I Calculate the Circumference? c θ 360 = c C C = C * 360 θ Θ= Shadow Angle c = distance between shadow area and no shadow area C = Circumference of Earth ***how did we get to C=?***

9. Let’s Look at a Ruler Example