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resresd
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in a circle with perimeter of 20cm a sector has radius r, angle θ radians and area Acm^2
prove that A= 25-(r-5)^2
A=1/2 r^2 θ
c=2Πr
the only thing that I can think to do is c=2Πr therefore 20=2Πr
10=Πr r=10/Π
so then A=1/2 r^2 θ
=1/2 (10/Π)^2 θ
= θ (100/2Π^2)
prove that A= 25-(r-5)^2
A=1/2 r^2 θ
c=2Πr
the only thing that I can think to do is c=2Πr therefore 20=2Πr
10=Πr r=10/Π
so then A=1/2 r^2 θ
=1/2 (10/Π)^2 θ
= θ (100/2Π^2)
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