Question

The diameters of two circles are 3.5 cm and 4.2 cm. Find the ratio of the area smaller circle to that of the bigger circle.​

Answer 1

Answer:

The ratio is 25:36

Step-by-step explanation:

Given:

The diameter of smaller circle = 3.5cm = 35mm

The diameter of bigger circle = 4.2cm = 42mm

To Find:

Find the ratio of the area smaller circle to that of the bigger circle.

Solution:

We know that,

Radius of smaller circle will be = 35/2 = 17.5 mm

Radius of bigger circle will be = 42/2 = 21 mm

Now,

Area of circle = πr²

Area of smaller circle = π × (17.5)²

Area of smaller circle = 3.14 × 17.5 × 17.5

Area of smaller circle = 962.5 mm²

Area of bigger circle = π × (21)²

Area of bigger circle = 3.14 × 21 × 21

Area of bigger circle = 1386 mm²

Ratio will be :-

=> 962 : 1385

=> 25 : 36