Question 674995
Circle A has {{{1/2}}} the area of circle {{{B}}}. The radius of circle B is {{{r=6 cm}}}.

{{{B=r^2*pi}}}

{{{B=(6cm)^2*pi}}}

{{{B=36cm^2*pi}}}


{{{A=r[1]^2pi}}}


{{{36cm^2*pi/2=r[1]^2pi}}}


{{{36cm^2/2=r[1]^2}}}


{{{18cm^2=r[1]^2}}}


{{{sqrt(18cm^2)=r[1]}}}


{{{4.24cm=r[1]}}}.........the radius of circle A (exact number 4.2426406871192851464050661726291)


{{{A=(4.24cm)^2pi}}}


{{{A=18cm^2pi}}}