The central angle is the measure of a minor arc. The degree measure of a
major arc is 360 degrees minus the degree measure of it's minor arc.
The degree measure of a semicircle is 180 degrees, half of 360.

Finding the length of an arc:

r is radius of the circle and M is the degree measure of an arc of the
circle, the length,L, of the arc is given by the following:
L= M/360 degrees(2Pi r)

## Section 9.1

## Objectives:

## Definitions:

at a given distance from a point within it called the center.Circle:a circle is a closed plane curve consisting of all points

sphere to the circumference or surface:Radius:a straight line extending from the center of a circle or(the radius of a circle is half the diameter.)

of the circle.Chord:a segment in which its endpoints line up on the circle.Diameter:a diameter is a cord which it includes the center point

endpoints of the diameter. (it is also known as theArc:a part of the circle were it isn`t broken.Endpoints: any points that had divided into two parts.Semicircle:it is an arc which the endpoints are thehalf circle)

is in the center of the circle.Minor arc:It is an arc that is shorter then the semicircle.Major arc:It is the arc that is longer then the semicircle.Central angle:it is an angle in the plane whose vertex

of the central angle and the other points are inside the angle.Intercepted arc: When the endpoints of an arc are on the sides## click here to see the equation of a circle

## Arc Length:

L=M/360°{2(3.14)r}-or-

L=M/360°(2r)

## Degree measure of arcs:

The central angle is the measure of a minor arc. The degree measure of amajor arc is 360 degrees minus the degree measure of it's minor arc.

The degree measure of a semicircle is 180 degrees, half of 360.

## Finding the length of an arc:

r is radius of the circle and M is the degree measure of an arc of thecircle, the length,L, of the arc is given by the following:

L= M/360 degrees(2Pi r)