360 likes | 602 Views
10-6 Circles and Arcs. Learning Goals 1. To find the measures of central angles and arcs. 2. To calculate the circumference and arc length. What is the measure of the angle all the way around B?. B. C. What is the measure of the angle all the way around B? 360˚. B. C.
E N D
Learning Goals1. To find the measures of central angles and arcs.2. To calculate the circumference and arc length.
What is the measure of the angle all the way around B? 360˚ B C
If m ABC = 60°, A B C
Central AngleAn angle whose vertex is at the center of a circle. Central Angle
ArcsThe sections of the circle separated by the central angles. arcs
Arcs are measured by their corresponding central angle. m ABC = 80 m AC = ? A 80° B C D
Arcs are measured by their corresponding central angle. m ABC = 80 m AC = 80 A 80° B C D
Arcs are measured by their corresponding central angle. m ABC = 80 m AC = 80 m ADC = ? A 80° B C D
Arcs are measured by their corresponding central angle. m ABC = 80 m AC = 80 m ADC = 280 A 80° B C D
Minor arc: less than 180° and 2 letters are used for the name.
Major arc: greater than 180° and 3 letters are used for the name.
***Important***When writing arc measure an “m” must be used.Example: m AC = 80°
***Important***When writing arc length no “m” is used.Example:PB = 3π
Calculating Arc Length Arc Measure • Circumference 360
Calculating Arc Length(which is the same as) Arc Measure • Circumference 360
Calculating Arc Length(which is the same as) Arc Measure • Circumference 360 Arc Measure • 2 π r 360
Calculating Arc Length1) Divide the arc measure by 360. P 90 360 4m 90° B J
Calculating Arc Length2) Find the circumference. P 90 360 4m 90° C = 2πr C = ? B J
Calculating Arc Length2) Find the circumference. P 90 360 4m 90° C = 2πr C = 8π B J
Calculating Arc Length3) Multiply the two. P 90 360 4m 90° C = 2πr C = 8π B J 90 • 8π = 2π 360
Calculating Arc Length PB = P 4m 90° B J 2π
Turn to page 654.9, 10, 33, 3411-18, 24-26, 29-32, 39-43, 485 Points: 100% Complete 4 Points: 80% Complete 3 Points: 60% Complete 2 Points: 40% Complete 1 Point: 20% Complete