Question

from a square cardboard of side 21cm a circle of maximum area is cut out, find the area of the cardboard left if the diametre of the circle is 21cm​

Answer 1

Answer:

94.64 sq.cm

Step-by-step explanation:

area of square cardboard = 21 ×21 = 441

area of circular cardboard cut out = π r²

here r = 10.5

=π × 10.5²

= 346.36

area left = 441 - 346.36

= 94.64 square unit

Answer 2

Answer:

Step-by-step explanation:

Given,

Side of square = 21 cm

Diameter of circle = 21 cm

To Find,

Area of the cardboard left.

Formula to be used,

Area of the square = Side × Side

Area of the circle = πr²

Solution,

At first, we will find the area of the square,

⇒ Area of the square = Side × Side

⇒ Area of the square = 21 × 21

⇒ Area of the square = 441 cm².

Now, we will find the area of the circle,

Radius = 21/2 = 10.5 cm

⇒ Area of the circle = πr²

⇒ Area of the circle = 22/7 × 10.5 × 10.5

⇒ Area of the circle = 346.5 cm².

       

Area of the cardboard left = Area of (Square - Circle)

⇒ Area of the cardboard left = 441 - 346.5

⇒ Area of the cardboard left = 95.5 cm²

Hence, the area of the cardboard left is 95.5 cm².