Calculate the area of a circle with a radius of 100 m; 20 cm Calculate the volume of the ball, the radius of which is 3 cm; 1m.

1. The area of the circle is found by the formula S = Пr ^ 2, where r is the radius of the circle.

a) S =П × 100 ^ 2 = 3.14 × 10000 = 31400 (m ^ 2);

b) S = П × 20 ^ 2 = 3.14 × 400 = 1256 (cm ^ 2).

2. The volume of the ball is found by the formula V = (4/3) ПR ^ 3, where R is the radius of the ball.

a) V = 4/3 × П × 3 ^ 3 = 4/3 × 3.14 × 27 = 4/3 × 314/100 × 27 = (4 × 314 × 27) / (3 × 100) = 33912 / 300 = 11304/100 = 113.04 (cm ^ 3);

b) V = 4/3 × П × 1 ^ 2 = 4/3 × 3.14 × 1 = 4/3 × 314/100 = (4 × 314) / (3 × 100) = 314 / (3 × 25 ) = 314/75 = 4 14/75 (m ^ 3).

Answer: 1. a) 31400 m ^ 2; b) 1256 cm ^ 2; 2.a) 113.04 cm ^ 3; b) 4 14/75 m ^ 3.