Question

the radii of two circles are 12 cm and 5cm respectively. find the radius of the circle having area equal to the sum of the two circles

Answer 1

Hope this will help you ....

Answer 2

r1=12 
r2=5
radius of new circle =R
area of new circle =sum of areas of both circles 

 πr1^2=144$\pi$

$\pi$r2^2=25$\pi$

required area is =  144$\pi$ + 25$\pi$
  \pi [/tex]R^2    =  169$\pi$[tex] 
R^2=169
R=13