Circle Vocabulary A Journey into the World of Circles… Homework: Lesson 1.7/1-11, 13, 15, all; odds

Definitions Objective: Have students understand the common definitions associated with circles such as radius, chord, and tangent, as well as the definition of a circle itself

What is a Circle? A circle is defined as…  The set of all points in a plane that are equidistant (radius) from a given point (center).

Circle Names A circle is named by its center Since the center is a point we use the circle notation and the point’s name A

Basic Parts of a Circle Interior of a Circle points A, B, C ON the circle point D Exterior of a Circle points E, F, G

Your Turn Lesson 1.7 – Circles  Turn to pages  Read the lesson  Write each bold faced word and its definition  On page 70: complete the investigation on the 3 indicated circle terms

Segments of a Circle Chord is a segment whose endpoints are on the circle

Segments of a Circle Diameter is a chord that passes through the center of the circle. The Diameter is the longest chord across a circle.

Segments of a Circle Radius – a segment that has the center as one endpoint and a point on the circle as the other endpoint. Don’t forget…  A diameter is made up of two radii  All radii, in the same circle, are congruent

Diameter, Chord or Radius?

Lines that Intersect a Circle

Lines that Intersect a Circle

Special Cases of Tangent Lines

Common Tangent Types Common External Tangent Common Internal Tangent

Recap… Identify the following by their correct vocabulary name

Concentric Circles Concentric circles are circles with a common center and different length radii. The region between two concentric circles of different radii is called an annulus. concentricradii annulus

Congruent Circles Circles are congruent circles if they have the same length radius.

ARC An arc of a circle is the continuous part of the circle btwn the 2 endpoints. An arc is a piece of the circle.

Semicircles Arc of a circle whose endpoints are the endpoints of a diameter of the circle. (3 letter names) D F

Minor arcs Arc of a circle whose measure is smaller than 180°. (2 letter names) S T

Major arcs Arc of a circle whose measure is between 180 ˚ and 360˚. (3 letter names) X T

Identify a minor,a major & a semicircle arc

CENTRAL ANGLE- is an angle with it’s vertex at the center and whose legs are radii of the circle. A PD <APD is a central angle in circle P

Central Angle & Intercepted Arc The degree measure of a central angle is equal to the degree measure of its intercepted arc. W X A

INSCRIBED ANGLE An angle with it’s vertex ON the circle and whose legs are chords of the circle. <AOB is an inscribed angle in circle P

In summary….. minor major