Calculate the approximate area of a circle if its radius is 7 cm.

Given:
circle;
circle radius R = 7 cm;
Find: S- ?;
Solution:
1) Since we are given a circle, for a start, we write down the formula for finding the area of a circle: S = pi * R ^ 2.
2) Since the number pi is not an integer and an infinite number of digits follow after the decimal point, in mathematics they take the value at which pi = 3.14.
3) For an approximate answer, take the value pi = 3.14, and the radius of the circle R = 7 cm. Substitute the values and find the area of the circle: S = 3.14 * 7 ^ 2 = 3.14 * 49 = 153.86 cm ^ 2 ≈ 154 cm ^ 2.
Answer: Area of a circle: S≈ 154 cm ^ 2.