The above figure shows  and  intersecting at E. List all the statements about the angles in this diagram that you think are true (see #1 for an example). Use the notation  to denote “the measure of angle DEA”. Assume all measures are relative arcs.























Go to Click on the Test your hypotheses link. Use the GSP sketch to test your hypotheses or to make even more hypotheses. (Note that GSP gives angle measures in degrees.)


On the back of this sheet, list the hypotheses that seem to be true. Pick one of these hypotheses. Provide an argument for why it must be true.

These hypotheses seem to be true:























Here is an argument that hypothesis #___ is true.