1. Lesson 1 J.Byrne 2015

2. Parts of a Circle A circle is a plane figure that has one continuous line called its Circumference. A straight line that touches the circumference in two places is called a Chord. The longest chord in a circle is the Diameter. The Diameter crosses the circles centre point. The Radius is the distance from the centre point to the circumference. J.Byrne 2015

3. Parts of a Circle The area between a chord and the circumference is called a Segment. The area between two radii is called a Sector. A section of the circumference is called an Arc. A quarter of a circle is called a Quadrant. Half of a circle is called a Semicircle. J.Byrne 2015

4. Circles Circles drawn from the same centre point are called Concentric Circles. Circles drawn from different centre points are called Eccentric Circles. J.Byrne 2015

5. Circles In a semicircle a triangle drawn from both ends of the diameter to a point on the circumference will always be a right angled triangle This is important as you will see later when we draw Tangents to circles J.Byrne 2015

6. Finding the centre of a circle If you have two chords of a circle you can find the centre of the circle. Bisect both chords and where these lines intersect is your centre point J.Byrne 2015

7. Example Question Redraw the outline of the Trophy below. You will have to use what you have learned so far to locate the centre. J.Byrne 2015

8. Freehand Circle http://www.youtube.com/watc h?v=-dwjsvVvwKk http://www.youtube.com/watc h?v=-dwjsvVvwKk J.Byrne 2015