You will need

- Ruler, pencil, eraser.

Instruction

1

Ball is a special case of the simplest three-dimensional figure. Through it, you can spend an infinite amount of sections, and any of them would be around. This happens regardless of how close the section is to the center of the ball. To calculate

**the area of**the resulting**cross-section**is the easiest in that case, if it is carried out through the center of a ball whose radius is known. In this case,**the area****of the cross section**is equal to:S=NR^2.2

The other figure,

**the area****of the cross section**which you want to find in geometry problems is a parallelepiped. It has edges, and faces. Face is one of the planes of a parallelepiped (cube), and rib - side. The parallelepiped whose edges and faces are equal is called a cube. All**sections**of the cube squares. Knowing this property, calculate**the area of****cross-section**-square:S=a^2, where a is the edge of the cube and the side**section**.3

If the conditions of the problem given a regular parallelepiped, in which all faces are different, the cross section can be a square and a rectangle with different sides. The cross section drawn parallel to the two square faces is a square, and the cross section drawn parallel to two rectangular - rectangle. If the section passes through the diagonal of the parallelepiped, it is also a rectangle.

4

The area of the square

**cross-section**parallelepiped can be found using the same formula as for a**cross-section**of the cube. If the cross section of the parallelepiped is a rectangle, find it, knowing two parameters, the length and width of the two rectangular faces:S=a*b, where a is the edge length, b -width of the verge.Diagonal cross section of a parallelepiped find by multiplying the diagonal of the bottom base to the height of the parallelepiped:S=d*h where d is the diagonal of the base, h is the height of the base.5

Cone - one of the figures of rotation,

**the cross section**of which can have different form. If you cut the cone parallel to the lower base section is a circle and if we draw a parallel section in half through the top of the cone, you get a triangle. In other cases,**section**mi will be a trapezoidal shape.If the cross section is a circle, calculate its**area**according to the following formula:S=NR^2.Square**cross-section**, which is a triangle is equal to the product of half the base to the height:S=1/2f*h , where f is the base of the triangle, h is the height of the triangle.