Introduction to Adjacent Angles

If two angles are placed adjacent (beside each other) and the outer edges of these angles makes a right angle then the angles add to 90 degrees.
Move the slider (located in top left of axis) to four different positions. Write down the values for angle BCD and angle DCF at each position. Add the two angles together then record what you notice about each position. Make sure you keep the values for each position of the slider separate.