Hold down the shift key and click and drag on the window to move the axes. Hold down the shift key and scroll down/up to zoom in/out.
In this application, you can click and drag points B, C, and D to form angles using 2 rays, 3 rays, or 2 lines.

Check “2 Ray”.
[1] Make an angle for each classification: acute, right, obtuse, and straight. Record the angle measure and sketch the angle.
[2] Can you make a 0° angle? What does it look like?
Uncheck “2 Ray” and check “3 Ray”.
[3] Place D in the interior of ∠BAC.
a. Sketch your figure.
b. What are the measures of the three angles that these three rays form?
c. What is the relationship between these measures?
d. Move point D back and forth, keeping it in the interior of ∠BAC. As you move it, what do you observe about the measures of the angles?
[4] Move B, C, and D so that all three angles are the same measure.
a. Sketch the figure.
b. What are the measures of the angles?
[5] Move B, C, and D so that two angles form a linear pair.
a. Sketch the figure.
b. What are the measures of the angles?
[6] Move B, C, and D so that two angles are complementary.
a. Sketch the figure.
b. What are the measures of the angles?
[7] Move B, C, and D so that two angles are supplementary.
a. Sketch the figure.
b. What are the measures of the angles?
Uncheck “3 Ray” and check “2 Line”.
[8] Name a pair of vertical angles.
[9] Make the lines perpendicular.
a. Sketch the graph.
b. How do you know the lines are parallel?
[9] Play around with the program. Look for patterns. If you think you see something that might be true, make a conjecture.