Find the area of a circle if the length of 1/3 of the circumference of this circle is 12.4 cm.

Given:
Circle;
1 / 3l = 12.4 cm;
π ≈ 3.1;
S =?
Decision:
1. Find the radius of the circle based on the given circumference.
The formula for the circumference is as follows.
l = 2πR;
Then 1/3 of the circumference is equal to:
1 / 3l = 2πR / 3;
R = 1 / 3l: 2π / 3;
R = 12.4: 2 * 3.1 / 3 = 12.4 * 3/2 * 3.1 = 2 * 3 = 6 (cm);
2. The area of a circle is calculated by the formula:
S = πR ^ 2;
S = 3.1 * 6 ^ 2 = 3.1 * 36 = 111.6 (sq. Cm);
Answer: 111.6 sq. cm.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.