1. Exploring the properties of circles
Circle geometry
Exploring the properties of circles

2. Exploring angles in circles
Once you start playing with creating lines and angles in a circle, you can recognize some properties or characteristics that are true. T
The line segment TB has both its endpoints on the circle.
It is called a chord. B

3. Exploring angles in circles
When an angle radiates from the centre of the circle to the edge of the circle, it is called a central angle. T C B

4. Exploring angles in circles
An angle that is formed by two chords that share a common endpoint is called an inscribed angle T R C
The arc of a circle is a portion of the circumference usually contained by two endpoints B

5. Exploring angles in circles
Draw a large circle
Label the centre point A
Construct a chord, label it BC
Create a central angle ∠BAC
Measure this central angle
Create an inscribed angle ∠BDC
Measure this inscribed angle
How does it compare to the central angle?
Create another inscribed angle ∠BEC
How does this compare to the other inscribed angle?

6. Exploring angles in circles
What truths have you discovered?
Stating these truths in mathematical terms:
Inscribed angles subtended by the same arc are congruent.
Angles that are formed by the endpoints of an arc are called subtended angles
The measure of a central angle is twice the measure of an inscribed angle which is subtended by the same arc.

7. Work it girls! Textbook page 382-383 Page 383 Complete 3, 4, 5
Complete 6, 7 (Hint: Pythagoras is your friend)