Exercise 60 Page 657

The length of an arc of a circle is the product of the measure of the arc divided by 360 and the circumference of the circle. length of AB=mAB/360 * 2π r

We are told that the measure of the desired arc is 60^(∘), the radius of the circle is 12 centimeters, and we want to find its arc length.

If we let A and B be the endpoints of our arc, we can substitute m AB= 60 and r=12 in the formula for arc length and simplify.

Length of AB=mAB/360 * 2π r

SubstituteII

mAB= 60, r= 12

Length of AB=60/360 * 2π (12)

▼

Evaluate right-hand side

CommutativePropMult

Commutative Property of Multiplication

Length of AB=60/360 * 2(12)π

Multiply

Multiply

Length of AB=60/360 * 24π

MoveRightFacToNum

a/c* b = a* b/c

Length of AB=1440/360* π

CalcQuot

Calculate quotient

Length of AB=4π

The length of the arc is 4π centimeters. Therefore, the correct option is B.