Section 6-1
Angles and Radian Measure
Degree/Radian Conversion Formulas
Change 115° to radian measure in terms of π23π/36
Change radians to degree measure.
-157.5°
Evaluate Cos 4π/3
Evaluate tan 5π/4
Circular Arc Central angle
The length of any circular arc s is equal to the product of the measure of the radius of the circle r and the radian measure of the central angle θ that it subtends. s= rθ
sθ
Given a central angle of 125°, find the length of its intercepted arc in a circle of radius 7 centimeters. Round to the nearest tenth.
125°= 125° x π/180° = 25 π/36 or 2.18
s=2.18 x 7= 15.3
Page 348 5-12
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