The area of a circle is proportional to the square of its radius. A small circle of radius 3 cm is drawn within a larger circle of radius 5 cm. Find the ratio of the areaof the annular zone to the area of the larger circle. (Area of the annular zone is the difference between the area of the larger circle and that of the smaller circle).
Area of circle = $$\pi r^2$$
Area of annular zone = $$\pi (5^2 - 3^2) = 16 \pi$$ sq. units
Area of larger circle = $$\pi * 5^2 = 25 \pi$$ sq. units
=> Required ratio = 16 : 25
Create a FREE account and get:
Quick, easy and effective revision
