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September 23, 2014

September 23, 2014

Posted by **Anonymous** on Sunday, January 20, 2013 at 4:36am.

20p cm^2

find the radius of the circle.

- maths-urgently -
**Reiny**, Sunday, January 20, 2013 at 8:50amlet the radius be r

circumference = 2πr

area = πr^2

πr^2/20π = 2πr/5π

r^2/20 = 2r/5

5r^2 = 40r

r^2 - 8r = 0

r(r-8) = 0

r = 8 or r = 0, of course we would want r > 0 to any area at all

r = 8

check:

if r = 8

circumf= 16π

area= 64π

20π/64π = 5/16

5π/16π = 5/16

All looks good

- maths-urgently -
**Anonymous**, Sunday, January 20, 2013 at 8:59amthank u @reiny

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