Find the area of a circle with a diameter of 12 cm. Find the area of a circle whose diameter

Find the area of a circle with a diameter of 12 cm. Find the area of a circle whose diameter is 2 times the diameter of the first circle.

A circle is a part of a plane that lies inside a circle.

The area of ​​the circle is equal to the product of the semicircle and the radius:

S = π r ^ 2, where:

r is the radius of the circle;

S is the area of ​​the circle.

r1 = d1 / 2, where

r1 – radius of the first circle;

d1 – diameter of the first circle.

r1 = 12/2 = 6 cm;

S1 = 3.14 * 62 = 3.14 * 36 = 113.04 cm2.

To calculate the area of ​​the second circle, we will use the same formula:

S = π r ^ 2.

If the diameter of the second circle is half the diameter of the first, then:

d2 = d1 / 2;

d2 = 12/2 = 6 cm.

r2 = d ^ 2/2;

r2 = 6/2 = 3 cm.

S2 = 3.14 * 32 = 3.14 * 9 = 28.26 cm2.

Answer: the area of ​​the first circle is 113.04 cm2; the area of ​​the second circle is 28.26 cm2.