GSP for 10/10

 Create a two page GSP file (named 4-1.gsp) and complete the following:

On page 1:

1. Draw a triangle using the segment tool.  Move the points around to make sure the triangle is connected.
2. Measure each angle of the triangle.
3. From the measure menu, choose calculate.  Find the sum of the three angles of the triangle.
4. Move the points of your triangle around to investigate the calculation.
5. Write a conjecture about your findings.

On page 2:

1.  Draw a ray.
2. Draw a segment that has the SAME endpoint as the ray.
3. Draw a third segment that shares one endpoint with the first segment and has one endpoint on the ray.
4. Your picture should look like this: 
   
5. Measure the interior angles of the triangle.
6. Measure <BCD.
7. Move the points around to notice any similarities. 
8. Write a conjecture about the exterior angle (<BCD) and the interior angle(s).
9. Use Calculate from the measure menu to prove your conjecture.