# Chapter 3 Geometry 9

## Math 9 Review chapter 3: Angle with a circle

Math 9 Review chapter 3: Angle with a circle 1. Summary of theory 1.1. Angle in the center An angle whose vertex coincides with the center of the circle is called a central angle. The two sides of the central angle intersect the circle at two points, thus dividing the circle into two arcs. For …

## Math 9 Chapter 3 Lesson 1: The central angle and the measure of the arc

Math 9 Chapter 3 Lesson 1: The central angle and the measure of the arc 1. Summary of theory 1.1. Angle in the center An angle whose vertex coincides with the center of the circle is called a central angle. The two sides of the central angle intersect the circle at two points, thus dividing …

## Math 9 Chapter 3 Lesson 2: The relationship between bow and string

Math 9 Chapter 3 Lesson 2: The relationship between bow and string 1. Summary of theory 1.1. Theorem 1 For two minor arcs in the same circle or two equal circles: a) Two equal arcs stretch two equal strings b) Two equal strings stretch two equal arcs – (stackrelfrown{AB}=stackrelfrown{CD}Rightarrow AB=CD) – (AB=CDRightarrowstackrelfrown{AB}=stackrelfrown{CD}) 1.2. Theorem 2 …

## Math 9 Chapter 3 Lesson 3: Inscribed angle

Math 9 Chapter 3 Lesson 3: Inscribed angle 1. Summary of theory 1.1. Define An inscribed angle is an angle whose vertex lies on a circle and whose sides contain two chords of that circle. The arc inside the angle is called the intercepted arc. The angle (widehat{BAC}) is called the inscribed angle, the intercepted …