Given,
Radii of the two circles are 6 cm and 8 cm
Area of circle with radius 8 cm = π (8)2 = 64π cm2
Area of circle with radius 6cm = π (6)2 = 36π cm2
Sum of areas = 64π + 36π = 100π cm2
Let the radius of the circle be x cm
Area of the circle = 100π cm2 (from above)
πx2 = 100π
x = √100 = 10 cm
Therefore, the radius of the circle is 10 cm.