Chapter 16 Circle theorems

16.1 Radii and Chords

A radius is a distance from the center to the circumference of a circle. It is half of the circle's diameter. A chord is a straight line connecting two points on a circle. In this section, we learn about Circle Theorems, Radii and Chords.

16.2 Tangents

A tangent is a straight line that touches a circle at one point only. The angle between a tangent and the radius is 90°. In this section, we learn about Using Tangent and Chord Properties, Intersecting chords and tangents.

16.3 Angles in Circles 1

The angle at the centre of a circle is twice the angle at the circumference when both are subtended by the same arc. In this section, we learn about Circles and Triangles Introduction, Angle Subtended At Centre, Angles in Semicircle, Calculating Angles In a Circle.

16.4 Angles in Circles 2

A cyclic quadrilateral is a quadrilateral with all four vertices on the circumference of a circle. In this section, we learn about angles subtended by arc, cyclic quadrilateral, Alternate Segment Theorem, Angles In The Alternate Segment.

16.5 Applying Circle Theorems

Angles subtended at the circumference by the same arc are equal. The angle in a semicircle is a right angle. In this section, we learn about Circle theorems.