S1_Chapter 9.3 Angles Inside

The figure above shows a rectangle with a point (C) inside. The point is joined to two adjacent corners (A and B). The angles at A, B and C are shown. Try to drag the point C and move freely inside the rectangle. What do you notice?

What if we drag the C out of the rectangle? What happens?

What about a parallelogram? What's your observation?

What about a trapezium? What's your observation?

Now if you randomly draw a quadrilateral, is your observation different from the previous ones?