Geometry: Quiz - Chapter 9

Arc length

linear meaurement in inches, ft, cm…

arc measure/angle

degress

find length of arc

1. find circumference of whole circle

2. figure out what fraction of the whole circle the arc represents

3. multiply the circumference by the fraction

formula for arc length

arc length (L) = x/360 (circumfernce) OR arc length (L) = x/360 (2pier)

x is the measure of the central angle

formula for area of sector

Asector = x/360(area of circle) OR Asector = x/360(pier²)

circle

2D shape where every point is equidistant from the center

radius

distance from center to any point on the circle

chord

line segment that connects any 2 points on the circle

diameter

a chord that goes through the center (2 times length of radius)

secant

line that intersects the circle in two places

tangent

line that intersects the circle once

point of tangency

the point where the tangent intersects the circle

central angle

formed by 2 radii and the vertex is the center of the circle

inscribed angle

formed by 2 chords and vertex is on the circle

arc

a piece of the circumference of the circle

minor arc

arc that is less than semicircle

less than 180, use 2 letters to name

major arc

arc that is more than a semicircle

more than 180, three letters going start, through, end

semicircle

exactly half of the circle

exactly 180

circle area formula

A=πr²

circumfernce circle formual

C=2πr

the measure of the arc formed by the endpoints of a central angle is

the measure of the arc formed by the endpoints of a central angle is equal to the measure of the central angle

an intercepted arc is the arc that lies between the

an intercepted arc is the arc that lies between the sides of an inscribed angle

the measure of the inscribed angle is equal to

the measure of the inscirbed angle is equal to ½ the measure of its intercepted arc

if an inscirbed angle intercepts a diameter

if an inscribed angle intercepts a diameter, then it is a right angle

if a quadrilateral is inscribed in a circle

if a quadrilateral is inscribed in a circle, then its opposite angles are supplementary

the measure on an inscribed anlge is equal to

the measure on an inscribed angle is equal to half of the measure of its intercepted arc