The radius of two circles are 10 cm and 24 cm.  The radius of a circle whose area is sum of area of these two circles is?

36 cm 17 cm 34 cm   26 cm

26 cm

area of circle C = area of circle A + area of circle B                   πr2 = πr12 + πr22               ⇒  r2  = r12 + r22              ⇒   r2  = 102 + 242                        = 100 + 576 = 676                    r = \(\sqrt {676}\) = 26 cm