The radius of B is 2.5cm.
What is a circle?
A circle is the locus of points equidistant from a common point which is called the center of the circle.
Analysis:
Area of circle A = π[tex]r^{2}[/tex]/4 = π[tex](15)^{2}[/tex]/4 = 225π/4
Area of circle B = π[tex]r^{2}[/tex]
But A = 9B
225π/4 = 9 x π[tex]r^{2}[/tex]
[tex]r^{2}[/tex] = 225/36 = 25/4
r = [tex]\sqrt{\frac{25}{4} }[/tex] = 5/2 = 2.5cm
Learn more about circle: brainly.com/question/24375372
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