# area of a sector of a circle

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• Jun 28th 2010, 07:22 AM
engineeringdaw
area of a sector of a circle
#1 a circle has a radius of 12cm. find the area of the sector of this circle of central angle is 315'.
#2 a clock has a pendulum 1,000 cm long. if it swings through an angle of 32', how far does the bottom of the bob travel in one swing?

need answers. pls help. :(( tnks!:)
• Jun 28th 2010, 07:41 AM
Chris L T521
Quote:

Originally Posted by engineeringdaw
#1 a circle has a radius of 12cm. find the area of the sector of this circle of central angle is 315'.
#2 a clock has a pendulum 1,000 cm long. if it swings through an angle of 32', how far does the bottom of the bob travel in one swing?

need answers. pls help. :(( tnks!:)

Recall two formulas:

Area of a sector: $A=\tfrac{1}{2}r^2\theta$, where r is the radius of the circle and $\theta$ is the central angle in radians.

Length of an arc: $s=r\theta$, where r is the radius of the circle and $\theta$ is the central angle in radians.

In both of these problems, you're given the radius, but you just need to convert each angle from degrees to radians.

Do you know how to proceed?