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how do you find the radius of a sector when the angle is 20 degrees and the arc length is 12cm?

 May 28, 2014

Best Answer 

 #1
avatar+26367 
+7

$$b = \text{ arc length }= 12cm$$

$$\alpha = 20 \ensuremath{^\circ}$$

r = radius  ?

$$\boxed{b=2\pi r\frac{\alpha\ensuremath{^\circ}}{360\ensuremath{^\circ}}}$$

$$\\\\
\Rightarrow r = \dfrac{b*180\ensuremath{^\circ}}{\pi*\alpha\ensuremath{^\circ}} \\\\
r = \dfrac{12\;cm*180\ensuremath{^\circ}}{\pi*20\ensuremath{^\circ}}=34,377\;cm$$

The radius is 34.377 cm

 May 28, 2014
 #1
avatar+26367 
+7
Best Answer

$$b = \text{ arc length }= 12cm$$

$$\alpha = 20 \ensuremath{^\circ}$$

r = radius  ?

$$\boxed{b=2\pi r\frac{\alpha\ensuremath{^\circ}}{360\ensuremath{^\circ}}}$$

$$\\\\
\Rightarrow r = \dfrac{b*180\ensuremath{^\circ}}{\pi*\alpha\ensuremath{^\circ}} \\\\
r = \dfrac{12\;cm*180\ensuremath{^\circ}}{\pi*20\ensuremath{^\circ}}=34,377\;cm$$

The radius is 34.377 cm

heureka May 28, 2014

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