doke612

=Chapter 9=

Section 9.1

 * Chords and Arcs**

Circle - A set of points equidistant from a certain one point on a plane. Diameter - A line that cuts the //circle// in half, it has to pass through the center point. Radius - Half of the //diameter//. Chord - A line that passes through two points on the circle, but does not go through the center point. Arc - Unbroken part inbetween two labled points on the //circle//. Endpoints - The points at the begining and the end of the //arc//. Semicircle - An //arc// whose endpoints are the //endpoints// of the //diameter//. Minor Arc - An //arc// that is smaller than a //semicircle//. Major Arc - An //arc// that is bigger than a //semicircle.// Central Angle - An angle with the vertex on the center of the //circle.// Intercepted Arc - An //arc// with the endpoints are the same as the //central angle.//
 * Vocabulary**

To find the degree measure of a minor arc, all you have to know is that the central angle degree is the same as the minor arc degree. To find the degree measure of a major arc, you take 360 degrees and subtract the degree measure of the minor arc, which is the central angle. Finally, to find the arc length you take the degree measure, M, divided by 360 degrees, multiplied by 2(pi)r If the central angle is 56 degrees what is the major and minor arc degree? What is the length of the major arc if "r" = 6
 * Formulas**
 * Examples**

If the central angle is the same as the minor arc then the minor arc degree is 56. Then take 360 and subtract 56 from it. 360 - 56 = 304. the measure of the major arc degree is, 304. Now that we know the major arc measure, we can easily figure out the length, the equation: L= M/360 (2(pi)r) L= (304)/360 (2(pi)(6)) L= 8.4 (37.6) L= 316.6 units

Section 9.2

 * Tangents to Circles

Vocabulary** Secant - A line that intersects a circle at two points. Tangent - A line on the same plane as the circle that intersects at exactly one point. Point of Tangency - The point at which a tangent intersects a circle.

Sketch a circle. Draw the center point and a radius. Next draw a chord through the radius at a 90 degree angle. Name the center R, the point of intersecting of the chord and radius, U. The endpoints of the chord are V and G. finally the endpoint of the radius is N.
 * Example**