The circumference of the bottom surface of a cone is 12.56 cm and the height is 8 cm. Cut it into two equal halves from the top along the height, and the surface area increases by () square cm

The circumference of the bottom surface of a cone is 12.56 cm and the height is 8 cm. Cut it into two equal halves from the top along the height, and the surface area increases by () square cm

In this way, two triangles with the base of diameter and the base of height are added
12.56 / 3.14 * 8 / 2 * 2 = 32 (cm2)

The circumference of the bottom of a cone is 18.56 cm and the height is 8 cm. Cut it into two equal halves from the top along the height, and the surface area is increased by () square cm
The circumference of the bottom surface of a cone is 12.56 cm

12.56 △ 3.14 = 4 (CM)
4 * 8 * 1 / 2 * 2 = 32 (cm2)

The circumference of the bottom surface of a cone is 12.56 cm. Cut it in half along the height from the apex of the cone. The area of each section is 36 square cm. Find the original
Volume of cone

The diameter of the bottom surface is 12.56 △ 3.14 = 4cm
The section is a triangle
The bottom is the diameter
So the height is 36 × 2 △ 4 = 18 cm
The bottom radius is 4 △ 2 = 2 cm
So the volume is 3.14 × 2 × 2 × 18 × 1 / 3 = 75.36 cubic centimeter