If the area of a circle is 9pi cm^2, then what is the radius of this circle?

The equation of the area of a circle is A = pi*(r^2) Therefore seeing as we have got the area we must work backwards to be able to answer this question. First we shall start off with substituting into the equation the numbers that we do know. 9pi= pi*(r^2) The next step is to get all of the integers on to the same side 9pi/pi=r^2 9=r^2 Continue solving, making sure that what you do to one side you do to the other. 3cm=r