Find the area of a circle, considering pi equal to 22 \ 7, if: a) its radius is 7 cm; b) its diameter is 42 cm.

a) the formula for finding the area of a circle looks like this: S = pi * r squared. Where pi is a constant number equal to 22/7, r is the radius of the circle. Let’s substitute 7 centimeters in the formula instead of the radius and find the area of the circle. We get: S = pi * 7 * 7 = 49 * 22/7 = (49 * 22) / 7 = (7 * 22) / 1 = 154 square centimeters;
b) 1) 42: 2 = 21 centimeters – the radius of the circle;
2) in the formula S = pi * r squared, substitute 21 centimeters instead of r, and instead of pi the number 22/7 and we get: S = pi * 21 * 21 = 22/7 * 21 * 21 = (22 * 21 * 21) / 7 = (22 * 7 * 21) / 1 = 154 * 7 = 1,078 square centimeters.
Answer: 1,078 square centimeters.