Math.help pleaseA circle has an area of M cm2 and a circumference_英语解答

Math.help please
A circle has an area of M cm2 and a circumference of N cm.If M/N= 20,what is the radius of the circle,in cm?

人气：260 ℃　时间：2020-06-27 20:49:13

解答

because 2*π*r=N
π*r*r=M
so M/N=r/2=20
r=40cm