SOLUTION: please help : the measure of a central angle of a sector is 36 degrees. the arc length of the sector is 4pi cm. what is the radius of the circle.

Algebra ->  Algebra  -> Circles -> SOLUTION: please help : the measure of a central angle of a sector is 36 degrees. the arc length of the sector is 4pi cm. what is the radius of the circle.       Log On

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Question 567951: please help :
the measure of a central angle of a sector is 36 degrees. the arc length of the sector is 4pi cm. what is the radius of the circle.
Answer by josmiceli(7353) About Me  (Show Source):
You can put this solution on YOUR website!
+36+ degrees is +36%2F360+=+1%2F10+ of a full circle
Let +C+ = circumference
The arc length is +4%2Api+ cm
+4%2Api+=+%281%2F10%29%2AC+
+C+=+40%2Api+
The formula is:
+C+=+2%2Api%2Ar+
+40%2Api+=+2%2Api%2Ar+
+r+=+%28+40%2Api+%29+%2F+%28+2%2Api+%29+
+r+=+20+ cm