Relationships between chords and their distances from centre

Healey Lee
Objective: To investigate the angle between a chord and the line joining the centre of the circle and the mid-point of the chord.
1. Drag point N so that N is the mid-point of AB (i.e. AN = BN). (You may press the button .) 2. When AN = BN, what is the size of ∠ONB? ∠ONB = 3. Vary the position and the length of chord AB by dragging A or B. Repeat the steps in questions 1 and 2. What is the size of ∠ONB? Does the size of ∠ONB change as chord AB varies? 4. Compare the result of question 3 with your classmates’. What conclusion can you draw?