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Arc Lengths. Sections 10.2 and 11.4. Circumference. The circumference of a circle is found by using the formula C = 2 π r Arc length is a part of the circumference of a circle and is found by using a proportion. Arc Length. Central Angle.
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Arc Lengths Sections 10.2 and 11.4
Circumference • The circumference of a circle is found by using the formula C = 2πr • Arc length is a part of the circumference of a circle and is found by using a proportion. Arc Length
Central Angle • A central angle of a circle is an angle whose vertex is the center of the circle. • When we say the measure of an arc, we are referring to the degree measure. • When we say the length of the arc, we are referring to the portion of the circumference the arc covers. Measure of an Arc Length of an Arc
Notation • When naming an arc, for instance arc AB, we use the notation • When talking about the degree measure of an arc, we use the notation
Minor Arc • The measure of a minor arc is the measure of its centralangle. • The measure of the entire circle is 360o. The measure of a major arc is the difference between 360o and the measure of the related minor arc. Major Arc
Semicircle • A semicircle is an arc whose endpoints are the endpoints of a diameter.
Arc Addition Postulate • The measure of an arc formed by two adjacent arcs is the sum of the measures of the two arcs
Find the measure of each indicated arc below for circle P shown
Congruent Circles • Two circles are congruent circles if they have the same radius. • Two arcs are congruent arcs if the have the same measure and they are arcs of the same circle or of congruent circles. Congruent Arcs
Assignment • P. 661 #1-17, 21, 25(a)